diff --git a/sdk/runanywhere-commons/CMakeLists.txt b/sdk/runanywhere-commons/CMakeLists.txt
index bb0ee984c..19f6af6ef 100644
--- a/sdk/runanywhere-commons/CMakeLists.txt
+++ b/sdk/runanywhere-commons/CMakeLists.txt
@@ -90,6 +90,9 @@ elseif(APPLE)
 elseif(UNIX)
     set(RAC_PLATFORM_LINUX TRUE)
     set(RAC_PLATFORM_NAME "Linux")
+elseif(WIN32)
+    set(RAC_PLATFORM_WINDOWS TRUE)
+    set(RAC_PLATFORM_NAME "Windows")
 else()
     set(RAC_PLATFORM_NAME "Unknown")
 endif()
@@ -125,6 +128,57 @@ if(NOT DEFINED LIBARCHIVE_VERSION)
     set(LIBARCHIVE_VERSION "3.8.1")
 endif()
 
+# -----------------------------------------------------------------------------
+# Zlib: Bundle from source when system zlib is not available.
+# Windows (MSVC) and some cross-compilation targets don't ship zlib.
+# We try system first; if not found, build from source so libarchive gets it.
+# -----------------------------------------------------------------------------
+find_package(ZLIB QUIET)
+if(NOT ZLIB_FOUND)
+    message(STATUS "System zlib not found — bundling from source...")
+    FetchContent_Declare(
+        zlib_src
+        GIT_REPOSITORY https://github.com/madler/zlib.git
+        GIT_TAG        v1.3.1
+        GIT_SHALLOW    TRUE
+    )
+    # Prevent zlib from installing or building examples
+    set(ZLIB_BUILD_EXAMPLES OFF CACHE BOOL "" FORCE)
+    set(SKIP_INSTALL_ALL ON CACHE BOOL "" FORCE)
+    set(SKIP_INSTALL_LIBRARIES ON CACHE BOOL "" FORCE)
+    set(SKIP_INSTALL_HEADERS ON CACHE BOOL "" FORCE)
+    set(SKIP_INSTALL_FILES ON CACHE BOOL "" FORCE)
+    # Save and restore BUILD_SHARED_LIBS
+    set(_SAVED_BSL_ZLIB ${BUILD_SHARED_LIBS})
+    set(BUILD_SHARED_LIBS OFF)
+    FetchContent_MakeAvailable(zlib_src)
+    set(BUILD_SHARED_LIBS ${_SAVED_BSL_ZLIB})
+
+    # Set cache variables so libarchive's find_package(ZLIB) picks up our build.
+    # For multi-config generators (Visual Studio), we point to the static lib
+    # output. The actual path is resolved at build time via target_link_libraries.
+    set(ZLIB_INCLUDE_DIR "${zlib_src_SOURCE_DIR};${zlib_src_BINARY_DIR}" CACHE PATH "" FORCE)
+    set(ZLIB_INCLUDE_DIRS "${zlib_src_SOURCE_DIR};${zlib_src_BINARY_DIR}" CACHE PATH "" FORCE)
+    # Use the CMake target name directly - this works because we link manually below
+    set(ZLIB_LIBRARY zlibstatic CACHE STRING "" FORCE)
+    set(ZLIB_LIBRARIES zlibstatic CACHE STRING "" FORCE)
+    set(ZLIB_FOUND TRUE CACHE BOOL "" FORCE)
+    # Create an imported ZLIB::ZLIB target that points to our zlibstatic
+    if(NOT TARGET ZLIB::ZLIB)
+        add_library(ZLIB::ZLIB ALIAS zlibstatic)
+    endif()
+    # On MSVC, set zlibstatic output to a known location so the linker can find it
+    if(MSVC AND TARGET zlibstatic)
+        set_target_properties(zlibstatic PROPERTIES
+            ARCHIVE_OUTPUT_DIRECTORY_RELEASE "${CMAKE_BINARY_DIR}/lib"
+            ARCHIVE_OUTPUT_DIRECTORY_DEBUG "${CMAKE_BINARY_DIR}/lib"
+        )
+    endif()
+    message(STATUS "Bundled zlib ready (v1.3.1)")
+else()
+    message(STATUS "Using system zlib: ${ZLIB_LIBRARIES}")
+endif()
+
 # -----------------------------------------------------------------------------
 # BZip2: Bundle from source for cross-compilation targets
 # Android NDK and Emscripten don't ship libbz2. macOS/iOS have it in the SDK.
@@ -156,6 +210,13 @@ if(NOT BZIP2_FOUND)
     set(BZIP2_INCLUDE_DIR "${bzip2_src_SOURCE_DIR}" CACHE PATH "" FORCE)
     set(BZIP2_LIBRARIES bz2_bundled CACHE STRING "" FORCE)
     set(BZIP2_FOUND TRUE CACHE BOOL "" FORCE)
+    # On MSVC, set output to a known location so the linker can find it
+    if(MSVC AND TARGET bz2_bundled)
+        set_target_properties(bz2_bundled PROPERTIES
+            ARCHIVE_OUTPUT_DIRECTORY_RELEASE "${CMAKE_BINARY_DIR}/lib"
+            ARCHIVE_OUTPUT_DIRECTORY_DEBUG "${CMAKE_BINARY_DIR}/lib"
+        )
+    endif()
     message(STATUS "Bundled BZip2 ready (v1.0.8)")
 else()
     message(STATUS "Using system BZip2: ${BZIP2_LIBRARIES}")
@@ -182,7 +243,7 @@ set(ENABLE_LIBXML2 OFF CACHE BOOL "" FORCE)
 set(ENABLE_EXPAT OFF CACHE BOOL "" FORCE)
 set(ENABLE_PCREPOSIX OFF CACHE BOOL "" FORCE)
 set(ENABLE_PCRE2POSIX OFF CACHE BOOL "" FORCE)
-set(ENABLE_LIBGCC OFF CACHE BOOL "" FORCE)
+set(ENABLE_LIBGCC ON CACHE BOOL "" FORCE)
 set(ENABLE_CNG OFF CACHE BOOL "" FORCE)
 set(ENABLE_TAR OFF CACHE BOOL "" FORCE)      # Don't build bsdtar binary
 set(ENABLE_CPIO OFF CACHE BOOL "" FORCE)     # Don't build bsdcpio binary
@@ -203,6 +264,32 @@ if(TARGET bz2_bundled AND TARGET archive_static)
     target_link_libraries(archive_static bz2_bundled)
 endif()
 
+# Link bundled zlib to libarchive if we built it from source
+if(TARGET zlibstatic AND TARGET archive_static)
+    target_link_libraries(archive_static zlibstatic)
+    target_include_directories(archive_static PRIVATE ${zlib_src_SOURCE_DIR} ${zlib_src_BINARY_DIR})
+endif()
+
+# On MSVC multi-config generators, libarchive references "zlibstatic.lib" and
+# "bz2_bundled.lib" by bare filename. The linker can't find them because they
+# are built into <config>/ subdirectories. Fix: redirect their output to a
+# single known directory and add it to the global linker search path.
+if(MSVC)
+    set(RAC_BUNDLED_LIB_DIR "${CMAKE_BINARY_DIR}/_bundled_libs")
+    foreach(_cfg Release Debug RelWithDebInfo MinSizeRel)
+        string(TOUPPER "${_cfg}" _CFG)
+        if(TARGET zlibstatic)
+            set_target_properties(zlibstatic PROPERTIES
+                ARCHIVE_OUTPUT_DIRECTORY_${_CFG} "${RAC_BUNDLED_LIB_DIR}")
+        endif()
+        if(TARGET bz2_bundled)
+            set_target_properties(bz2_bundled PROPERTIES
+                ARCHIVE_OUTPUT_DIRECTORY_${_CFG} "${RAC_BUNDLED_LIB_DIR}")
+        endif()
+    endforeach()
+    link_directories("${RAC_BUNDLED_LIB_DIR}")
+endif()
+
 message(STATUS "libarchive ready (v${LIBARCHIVE_VERSION})")
 
 # =============================================================================
@@ -234,6 +321,17 @@ if(CMAKE_CXX_COMPILER_ID MATCHES "Clang|GNU")
         add_compile_options(-fvisibility=hidden)
         add_compile_options(-ffunction-sections -fdata-sections)
     endif()
+elseif(MSVC)
+    # /W3 = reasonable warning level, /utf-8 = source/execution charset
+    # /Zc:__cplusplus = report correct __cplusplus value
+    # /EHsc = standard C++ exception handling
+    add_compile_options(/W3 /utf-8 /Zc:__cplusplus /EHsc)
+    # Suppress common harmless warnings in third-party code
+    add_compile_options(/wd4244 /wd4267 /wd4996)
+    add_compile_definitions(_CRT_SECURE_NO_WARNINGS NOMINMAX WIN32_LEAN_AND_MEAN)
+    if(CMAKE_BUILD_TYPE STREQUAL "Release")
+        add_compile_options(/O2 /DNDEBUG)
+    endif()
 endif()
 
 # =============================================================================
@@ -351,8 +449,11 @@ set(RAC_FEATURES_SOURCES
     src/features/embeddings/embeddings_component.cpp
     # Voice Agent
     src/features/voice_agent/voice_agent.cpp
-    # Result memory management
-    src/features/result_free.cpp
+    # Result memory management (weak symbol fallbacks)
+    # On MSVC, each service .cpp already provides strong definitions,
+    # so result_free.cpp (which uses __attribute__((weak)) on GCC/Clang)
+    # must be excluded to avoid LNK2005 duplicate symbol errors.
+    $<$<NOT:$<CXX_COMPILER_ID:MSVC>>:src/features/result_free.cpp>
 )
 
 # Platform services (Apple Foundation Models + System TTS + CoreML Diffusion)
@@ -420,7 +521,20 @@ if(RAC_BUILD_SHARED)
 endif()
 
 # libarchive - native archive extraction
-target_link_libraries(rac_commons PRIVATE archive_static)
+# PUBLIC on Windows because MSVC static libs don't propagate transitive deps
+if(WIN32)
+    target_link_libraries(rac_commons PUBLIC archive_static)
+    # Tell libarchive headers we're using the static library (not DLL)
+    target_compile_definitions(rac_commons PRIVATE LIBARCHIVE_STATIC)
+    if(TARGET zlibstatic)
+        target_link_libraries(rac_commons PUBLIC zlibstatic)
+    endif()
+    if(TARGET bz2_bundled)
+        target_link_libraries(rac_commons PUBLIC bz2_bundled)
+    endif()
+else()
+    target_link_libraries(rac_commons PRIVATE archive_static)
+endif()
 target_include_directories(rac_commons PRIVATE ${libarchive_SOURCE_DIR}/libarchive ${libarchive_BINARY_DIR})
 
 # Platform-specific linking
@@ -440,6 +554,12 @@ if(RAC_PLATFORM_ANDROID)
     target_link_libraries(rac_commons PUBLIC log)
 endif()
 
+if(RAC_PLATFORM_WINDOWS)
+    target_compile_definitions(rac_commons PRIVATE RAC_PLATFORM_WINDOWS=1)
+    # ws2_32 = Winsock, shlwapi = path utilities
+    target_link_libraries(rac_commons PUBLIC ws2_32 shlwapi)
+endif()
+
 set_target_properties(rac_commons PROPERTIES
     CXX_STANDARD 20
     CXX_STANDARD_REQUIRED ON
@@ -587,6 +707,9 @@ message(STATUS "  Services:     LLM, STT, TTS, VAD interfaces")
 if(APPLE AND RAC_BUILD_PLATFORM)
     message(STATUS "  Platform:     Apple Foundation Models, System TTS")
 endif()
+if(RAC_PLATFORM_WINDOWS)
+    message(STATUS "  Platform:     Windows (MSVC)")
+endif()
 if(RAC_BUILD_BACKENDS)
     message(STATUS "  Backends:     LlamaCPP=${RAC_BACKEND_LLAMACPP}, ONNX=${RAC_BACKEND_ONNX}, WhisperCPP=${RAC_BACKEND_WHISPERCPP}, WhisperKitCoreML=${RAC_BACKEND_WHISPERKIT_COREML}")
     if(RAC_BACKEND_RAG)
diff --git a/sdk/runanywhere-commons/CMakePresets.json b/sdk/runanywhere-commons/CMakePresets.json
index 6d45784cb..16b931a37 100644
--- a/sdk/runanywhere-commons/CMakePresets.json
+++ b/sdk/runanywhere-commons/CMakePresets.json
@@ -27,6 +27,44 @@
         "CMAKE_BUILD_TYPE": "Debug",
         "CMAKE_EXPORT_COMPILE_COMMANDS": "ON"
       }
+    },
+    {
+      "name": "windows-msvc",
+      "displayName": "Windows MSVC (all backends)",
+      "description": "Windows build with MSVC, all backends enabled",
+      "binaryDir": "${sourceDir}/build/windows",
+      "generator": "Visual Studio 17 2022",
+      "architecture": {
+        "value": "x64",
+        "strategy": "set"
+      },
+      "cacheVariables": {
+        "RAC_BUILD_BACKENDS": "ON",
+        "RAC_BACKEND_LLAMACPP": "ON",
+        "RAC_BACKEND_ONNX": "ON",
+        "RAC_BACKEND_RAG": "ON",
+        "RAC_BACKEND_WHISPERCPP": "OFF",
+        "RAC_BUILD_PLATFORM": "OFF",
+        "RAC_BUILD_TESTS": "ON",
+        "CMAKE_BUILD_TYPE": "Release"
+      }
+    },
+    {
+      "name": "windows-msvc-core",
+      "displayName": "Windows MSVC (core only)",
+      "description": "Windows build with MSVC, core library only (no backends)",
+      "binaryDir": "${sourceDir}/build/windows-core",
+      "generator": "Visual Studio 17 2022",
+      "architecture": {
+        "value": "x64",
+        "strategy": "set"
+      },
+      "cacheVariables": {
+        "RAC_BUILD_BACKENDS": "OFF",
+        "RAC_BUILD_PLATFORM": "OFF",
+        "RAC_BUILD_TESTS": "ON",
+        "CMAKE_BUILD_TYPE": "Release"
+      }
     }
   ]
 }
diff --git a/sdk/runanywhere-commons/VERSIONS b/sdk/runanywhere-commons/VERSIONS
index 47c030882..7f6cf7dfc 100644
--- a/sdk/runanywhere-commons/VERSIONS
+++ b/sdk/runanywhere-commons/VERSIONS
@@ -49,6 +49,9 @@ ONNX_VERSION_MACOS=1.23.2
 # Linux version (can use latest)
 ONNX_VERSION_LINUX=1.23.2
 
+# Windows version (can use latest)
+ONNX_VERSION_WINDOWS=1.23.2
+
 # =============================================================================
 # Sherpa-ONNX (via runanywhere-core)
 # =============================================================================
@@ -69,6 +72,9 @@ SHERPA_ONNX_VERSION_MACOS=1.12.18
 # Linux version
 SHERPA_ONNX_VERSION_LINUX=1.12.23
 
+# Windows version
+SHERPA_ONNX_VERSION_WINDOWS=1.12.23
+
 # =============================================================================
 # llama.cpp (LLM inference)
 # =============================================================================
diff --git a/sdk/runanywhere-commons/cmake/FetchONNXRuntime.cmake b/sdk/runanywhere-commons/cmake/FetchONNXRuntime.cmake
index f971d1aed..43a4b31e6 100644
--- a/sdk/runanywhere-commons/cmake/FetchONNXRuntime.cmake
+++ b/sdk/runanywhere-commons/cmake/FetchONNXRuntime.cmake
@@ -265,6 +265,39 @@ elseif(UNIX)
 
     message(STATUS "ONNX Runtime Linux library: ${onnxruntime_SOURCE_DIR}/lib/libonnxruntime.so")
 
+elseif(WIN32)
+    # Windows: Download Windows binaries
+    if(NOT DEFINED ONNX_VERSION_WINDOWS OR "${ONNX_VERSION_WINDOWS}" STREQUAL "")
+        message(FATAL_ERROR "ONNX_VERSION_WINDOWS not defined in VERSIONS file")
+    endif()
+
+    if(CMAKE_SIZEOF_VOID_P EQUAL 8)
+        set(ONNX_URL "https://github.com/microsoft/onnxruntime/releases/download/v${ONNX_VERSION_WINDOWS}/onnxruntime-win-x64-${ONNX_VERSION_WINDOWS}.zip")
+    else()
+        set(ONNX_URL "https://github.com/microsoft/onnxruntime/releases/download/v${ONNX_VERSION_WINDOWS}/onnxruntime-win-x86-${ONNX_VERSION_WINDOWS}.zip")
+    endif()
+
+    FetchContent_Declare(
+        onnxruntime
+        URL ${ONNX_URL}
+        DOWNLOAD_EXTRACT_TIMESTAMP TRUE
+    )
+
+    FetchContent_MakeAvailable(onnxruntime)
+
+    add_library(onnxruntime SHARED IMPORTED GLOBAL)
+
+    set_target_properties(onnxruntime PROPERTIES
+        IMPORTED_IMPLIB "${onnxruntime_SOURCE_DIR}/lib/onnxruntime.lib"
+        IMPORTED_LOCATION "${onnxruntime_SOURCE_DIR}/lib/onnxruntime.dll"
+    )
+
+    target_include_directories(onnxruntime INTERFACE
+        "${onnxruntime_SOURCE_DIR}/include"
+    )
+
+    message(STATUS "ONNX Runtime Windows library: ${onnxruntime_SOURCE_DIR}/lib/onnxruntime.lib")
+
 else()
     message(FATAL_ERROR "Unsupported platform for ONNX Runtime")
 endif()
diff --git a/sdk/runanywhere-commons/cmake/LoadVersions.cmake b/sdk/runanywhere-commons/cmake/LoadVersions.cmake
index 56bee13fa..b9d7a849f 100644
--- a/sdk/runanywhere-commons/cmake/LoadVersions.cmake
+++ b/sdk/runanywhere-commons/cmake/LoadVersions.cmake
@@ -56,10 +56,13 @@ message(STATUS "    ONNX_VERSION_IOS: ${RAC_ONNX_VERSION_IOS}")
 message(STATUS "    ONNX_VERSION_ANDROID: ${RAC_ONNX_VERSION_ANDROID}")
 message(STATUS "    ONNX_VERSION_MACOS: ${RAC_ONNX_VERSION_MACOS}")
 message(STATUS "    ONNX_VERSION_LINUX: ${RAC_ONNX_VERSION_LINUX}")
+message(STATUS "    ONNX_VERSION_WINDOWS: ${RAC_ONNX_VERSION_WINDOWS}")
 message(STATUS "  Sherpa-ONNX:")
 message(STATUS "    SHERPA_ONNX_VERSION_IOS: ${RAC_SHERPA_ONNX_VERSION_IOS}")
 message(STATUS "    SHERPA_ONNX_VERSION_ANDROID: ${RAC_SHERPA_ONNX_VERSION_ANDROID}")
 message(STATUS "    SHERPA_ONNX_VERSION_MACOS: ${RAC_SHERPA_ONNX_VERSION_MACOS}")
+message(STATUS "    SHERPA_ONNX_VERSION_LINUX: ${RAC_SHERPA_ONNX_VERSION_LINUX}")
+message(STATUS "    SHERPA_ONNX_VERSION_WINDOWS: ${RAC_SHERPA_ONNX_VERSION_WINDOWS}")
 message(STATUS "  Other:")
 message(STATUS "    LLAMACPP_VERSION: ${RAC_LLAMACPP_VERSION}")
 message(STATUS "    NLOHMANN_JSON_VERSION: ${RAC_NLOHMANN_JSON_VERSION}")
diff --git a/sdk/runanywhere-commons/include/rac/core/rac_platform_compat.h b/sdk/runanywhere-commons/include/rac/core/rac_platform_compat.h
new file mode 100644
index 000000000..e92af6d64
--- /dev/null
+++ b/sdk/runanywhere-commons/include/rac/core/rac_platform_compat.h
@@ -0,0 +1,151 @@
+/**
+ * @file rac_platform_compat.h
+ * @brief RunAnywhere Commons - Platform Compatibility Layer
+ *
+ * Provides POSIX-like APIs on Windows (MSVC) so that the rest of the codebase
+ * can use dirent.h, S_ISDIR, S_ISREG, etc. without #ifdef clutter.
+ *
+ * On non-Windows platforms this header is a no-op passthrough.
+ */
+
+#ifndef RAC_PLATFORM_COMPAT_H
+#define RAC_PLATFORM_COMPAT_H
+
+#ifdef _WIN32
+
+/* ---- POSIX string functions --------------------------------------------- */
+#include <string.h>
+#ifndef strcasecmp
+#define strcasecmp _stricmp
+#endif
+#ifndef strncasecmp
+#define strncasecmp _strnicmp
+#endif
+
+/* ---- stat / S_IS* macros ------------------------------------------------ */
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#ifndef S_ISDIR
+#define S_ISDIR(m) (((m) & _S_IFMT) == _S_IFDIR)
+#endif
+
+#ifndef S_ISREG
+#define S_ISREG(m) (((m) & _S_IFMT) == _S_IFREG)
+#endif
+
+#ifndef S_IFLNK
+#define S_IFLNK 0120000
+#endif
+
+#ifndef S_ISLNK
+#define S_ISLNK(m) (0) /* Windows does not have symlinks in the POSIX sense */
+#endif
+
+/* ---- dirent.h (minimal implementation) ---------------------------------- */
+/* Provides opendir / readdir / closedir using Win32 FindFirstFile API.       */
+
+#include <io.h>
+#include <windows.h>
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+
+#ifndef NAME_MAX
+#define NAME_MAX 260
+#endif
+
+struct dirent {
+    char d_name[NAME_MAX + 1];
+};
+
+typedef struct DIR {
+    HANDLE           hFind;
+    WIN32_FIND_DATAA fdata;
+    struct dirent    entry;
+    int              first;   /* 1 = first call to readdir */
+} DIR;
+
+static inline DIR* opendir(const char* path) {
+    if (!path || !*path) { errno = ENOENT; return NULL; }
+
+    size_t len = strlen(path);
+    /* Build search pattern: path\* */
+    char* pattern = (char*)malloc(len + 3);
+    if (!pattern) { errno = ENOMEM; return NULL; }
+    memcpy(pattern, path, len);
+    if (path[len - 1] != '\\' && path[len - 1] != '/') {
+        pattern[len++] = '\\';
+    }
+    pattern[len++] = '*';
+    pattern[len] = '\0';
+
+    DIR* dir = (DIR*)malloc(sizeof(DIR));
+    if (!dir) { free(pattern); errno = ENOMEM; return NULL; }
+
+    dir->hFind = FindFirstFileA(pattern, &dir->fdata);
+    free(pattern);
+
+    if (dir->hFind == INVALID_HANDLE_VALUE) {
+        free(dir);
+        errno = ENOENT;
+        return NULL;
+    }
+    dir->first = 1;
+    return dir;
+}
+
+static inline struct dirent* readdir(DIR* dir) {
+    if (!dir) return NULL;
+
+    if (dir->first) {
+        dir->first = 0;
+    } else {
+        if (!FindNextFileA(dir->hFind, &dir->fdata)) return NULL;
+    }
+    strncpy(dir->entry.d_name, dir->fdata.cFileName, NAME_MAX);
+    dir->entry.d_name[NAME_MAX] = '\0';
+    return &dir->entry;
+}
+
+static inline int closedir(DIR* dir) {
+    if (!dir) return -1;
+    FindClose(dir->hFind);
+    free(dir);
+    return 0;
+}
+
+#else /* !_WIN32 */
+
+#include <dirent.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#endif /* _WIN32 */
+
+/* ---- C++ helpers (available on all platforms) ---------------------------- */
+#ifdef __cplusplus
+#include <string>
+
+#ifdef _WIN32
+/**
+ * Convert a UTF-8 std::string to std::wstring for Windows wide-char APIs.
+ * Used by ONNX Runtime Session creation which requires wchar_t* on Windows.
+ */
+inline std::wstring rac_to_wstring(const std::string& s) {
+    return std::wstring(s.begin(), s.end());
+}
+inline std::wstring rac_to_wstring(const char* s) {
+    if (!s) return {};
+    return std::wstring(s, s + strlen(s));
+}
+/** On Windows, ONNX Runtime expects wchar_t* paths */
+#define RAC_ORT_PATH(p) rac_to_wstring(p).c_str()
+#else
+/** On non-Windows, ONNX Runtime expects char* paths */
+#define RAC_ORT_PATH(p) (p)
+#endif
+
+#endif /* __cplusplus */
+
+#endif /* RAC_PLATFORM_COMPAT_H */
diff --git a/sdk/runanywhere-commons/scripts/build-windows.bat b/sdk/runanywhere-commons/scripts/build-windows.bat
new file mode 100644
index 000000000..c5cc3b8dc
--- /dev/null
+++ b/sdk/runanywhere-commons/scripts/build-windows.bat
@@ -0,0 +1,336 @@
+@echo off
+setlocal enabledelayedexpansion
+
+:: =============================================================================
+:: build-windows.bat
+:: Windows build script for runanywhere-commons (x64, MSVC)
+::
+:: Usage: build-windows.bat [options] [backends]
+::        backends: onnx | llamacpp | all (default: all)
+::                  - onnx: STT/TTS/VAD (ONNX Runtime)
+::                  - llamacpp: LLM text generation (GGUF models)
+::                  - all: onnx + llamacpp (default)
+::
+:: Options:
+::   --clean     Clean build directory before building
+::   --shared    Build shared libraries (default: static)
+::   --test      Build and run tests
+::   --help      Show this help message
+::
+:: Examples:
+::   build-windows.bat                    Build all backends (static)
+::   build-windows.bat --shared           Build all backends (shared)
+::   build-windows.bat llamacpp           Build only LlamaCPP
+::   build-windows.bat onnx              Build only ONNX backend
+::   build-windows.bat --clean all        Clean build, all backends
+::   build-windows.bat --test             Build all + run tests
+::
+:: Prerequisites:
+::   - CMake 3.22+
+::   - Visual Studio 2022 (or Build Tools) with C++ workload
+:: =============================================================================
+
+set "SCRIPT_DIR=%~dp0"
+set "ROOT_DIR=%SCRIPT_DIR%.."
+set "BUILD_DIR=%ROOT_DIR%\build\windows-x64"
+set "DIST_DIR=%ROOT_DIR%\dist\windows\x64"
+
+:: =============================================================================
+:: Load Versions
+:: =============================================================================
+call :load_versions
+
+:: =============================================================================
+:: Defaults
+:: =============================================================================
+set "CLEAN_BUILD=0"
+set "BUILD_SHARED=OFF"
+set "BUILD_TESTS=OFF"
+set "RUN_TESTS=0"
+set "BUILD_ONNX=OFF"
+set "BUILD_LLAMACPP=OFF"
+set "BACKENDS="
+
+:: =============================================================================
+:: Parse Options
+:: =============================================================================
+:parse_args
+if "%~1"=="" goto :done_args
+if "%~1"=="--clean" (
+    set "CLEAN_BUILD=1"
+    shift
+    goto :parse_args
+)
+if "%~1"=="--shared" (
+    set "BUILD_SHARED=ON"
+    shift
+    goto :parse_args
+)
+if "%~1"=="--test" (
+    set "BUILD_TESTS=ON"
+    set "RUN_TESTS=1"
+    shift
+    goto :parse_args
+)
+if "%~1"=="--help" goto :show_help
+if "%~1"=="-h" goto :show_help
+
+:: Must be a backend argument
+set "BACKENDS=%~1"
+shift
+goto :parse_args
+
+:done_args
+
+:: Default backends = all
+if "%BACKENDS%"=="" set "BACKENDS=all"
+
+if "%BACKENDS%"=="all" (
+    set "BUILD_ONNX=ON"
+    set "BUILD_LLAMACPP=ON"
+) else if "%BACKENDS%"=="onnx" (
+    set "BUILD_ONNX=ON"
+) else if "%BACKENDS%"=="llamacpp" (
+    set "BUILD_LLAMACPP=ON"
+) else (
+    echo [ERROR] Unknown backend: %BACKENDS%
+    echo Usage: %~nx0 [options] [onnx ^| llamacpp ^| all]
+    exit /b 1
+)
+
+:: =============================================================================
+:: Print Header
+:: =============================================================================
+echo.
+echo ========================================
+echo  RunAnywhere Windows Build
+echo ========================================
+echo.
+echo  Architecture:  x64
+echo  Backends:      ONNX=%BUILD_ONNX%, LlamaCPP=%BUILD_LLAMACPP%
+if "%BUILD_SHARED%"=="ON" (echo  Library type:  Shared) else (echo  Library type:  Static)
+echo  Tests:         %BUILD_TESTS%
+echo  Build dir:     %BUILD_DIR%
+echo  Dist dir:      %DIST_DIR%
+echo.
+
+:: =============================================================================
+:: Prerequisites
+:: =============================================================================
+echo [CHECK] Checking prerequisites...
+
+where cmake >nul 2>&1
+if errorlevel 1 (
+    echo [ERROR] cmake not found. Install CMake 3.22+ and add to PATH.
+    exit /b 1
+)
+for /f "tokens=3" %%v in ('cmake --version 2^>^&1 ^| findstr /i "version"') do (
+    echo [OK] Found cmake %%v
+)
+
+:: Check for Visual Studio
+where cl >nul 2>&1
+if errorlevel 1 (
+    echo [WARN] cl.exe not in PATH. Attempting to find Visual Studio...
+    call :find_vs
+    if errorlevel 1 (
+        echo [ERROR] Visual Studio 2022 with C++ workload not found.
+        echo         Install from https://visualstudio.microsoft.com/
+        exit /b 1
+    )
+)
+echo [OK] MSVC compiler available
+
+:: =============================================================================
+:: Clean Build
+:: =============================================================================
+if "%CLEAN_BUILD%"=="1" (
+    echo [CLEAN] Removing previous build...
+    if exist "%BUILD_DIR%" rmdir /s /q "%BUILD_DIR%" 2>nul
+    if exist "%DIST_DIR%" rmdir /s /q "%DIST_DIR%" 2>nul
+)
+
+if not exist "%BUILD_DIR%" mkdir "%BUILD_DIR%"
+if not exist "%DIST_DIR%" mkdir "%DIST_DIR%"
+
+:: =============================================================================
+:: Configure
+:: =============================================================================
+echo.
+echo ========================================
+echo  Configuring CMake
+echo ========================================
+echo.
+
+cmake -B "%BUILD_DIR%" ^
+    -G "Visual Studio 17 2022" -A x64 ^
+    -DRAC_BUILD_BACKENDS=ON ^
+    -DRAC_BACKEND_ONNX=%BUILD_ONNX% ^
+    -DRAC_BACKEND_LLAMACPP=%BUILD_LLAMACPP% ^
+    -DRAC_BACKEND_WHISPERCPP=OFF ^
+    -DRAC_BACKEND_RAG=ON ^
+    -DRAC_BUILD_TESTS=%BUILD_TESTS% ^
+    -DRAC_BUILD_SHARED=%BUILD_SHARED% ^
+    -DRAC_BUILD_PLATFORM=OFF ^
+    "%ROOT_DIR%"
+
+if errorlevel 1 (
+    echo [ERROR] CMake configure failed.
+    exit /b 1
+)
+echo [OK] CMake configure complete
+
+:: =============================================================================
+:: Build
+:: =============================================================================
+echo.
+echo ========================================
+echo  Building
+echo ========================================
+echo.
+
+cmake --build "%BUILD_DIR%" --config Release -- /m
+if errorlevel 1 (
+    echo [ERROR] Build failed.
+    exit /b 1
+)
+echo [OK] Build complete
+
+:: =============================================================================
+:: Copy to Distribution Directory
+:: =============================================================================
+echo.
+echo [DIST] Copying libraries to distribution directory...
+
+if "%BUILD_SHARED%"=="ON" (set "LIB_EXT=dll") else (set "LIB_EXT=lib")
+
+:: Core library
+if exist "%BUILD_DIR%\Release\rac_commons.lib" (
+    copy /y "%BUILD_DIR%\Release\rac_commons.lib" "%DIST_DIR%\" >nul
+    echo [OK] Copied rac_commons.lib
+)
+
+:: ONNX backend
+if "%BUILD_ONNX%"=="ON" (
+    if exist "%BUILD_DIR%\src\backends\onnx\Release\rac_backend_onnx.lib" (
+        copy /y "%BUILD_DIR%\src\backends\onnx\Release\rac_backend_onnx.lib" "%DIST_DIR%\" >nul
+        echo [OK] Copied rac_backend_onnx.lib
+    )
+)
+
+:: LlamaCPP backend
+if "%BUILD_LLAMACPP%"=="ON" (
+    if exist "%BUILD_DIR%\src\backends\llamacpp\Release\rac_backend_llamacpp.lib" (
+        copy /y "%BUILD_DIR%\src\backends\llamacpp\Release\rac_backend_llamacpp.lib" "%DIST_DIR%\" >nul
+        echo [OK] Copied rac_backend_llamacpp.lib
+    )
+)
+
+:: Headers
+echo [DIST] Copying headers...
+if not exist "%DIST_DIR%\include" mkdir "%DIST_DIR%\include"
+xcopy /s /y /q "%ROOT_DIR%\include\rac" "%DIST_DIR%\include\rac\" >nul
+echo [OK] Copied headers
+
+:: =============================================================================
+:: Run Tests
+:: =============================================================================
+if "%RUN_TESTS%"=="1" (
+    echo.
+    echo ========================================
+    echo  Running Tests
+    echo ========================================
+    echo.
+
+    set "TEST_DIR=%BUILD_DIR%\tests\Release"
+    set "TESTS_PASSED=0"
+    set "TESTS_FAILED=0"
+
+    for %%t in (test_core test_extraction test_download_orchestrator) do (
+        if exist "!TEST_DIR!\%%t.exe" (
+            echo --- %%t ---
+            "!TEST_DIR!\%%t.exe" --run-all
+            if errorlevel 1 (
+                set /a TESTS_FAILED+=1
+            ) else (
+                set /a TESTS_PASSED+=1
+            )
+            echo.
+        )
+    )
+
+    echo ========================================
+    echo  Test Results: !TESTS_PASSED! passed, !TESTS_FAILED! failed
+    echo ========================================
+)
+
+:: =============================================================================
+:: Summary
+:: =============================================================================
+echo.
+echo ========================================
+echo  Build Complete!
+echo ========================================
+echo.
+echo  Distribution: %DIST_DIR%
+echo.
+dir /b "%DIST_DIR%\*.lib" 2>nul
+echo.
+echo  To use in your project:
+echo    Include: /I"%DIST_DIR%\include"
+echo    Link:    /LIBPATH:"%DIST_DIR%" rac_commons.lib
+echo.
+
+exit /b 0
+
+:: =============================================================================
+:: Subroutines
+:: =============================================================================
+
+:show_help
+echo Usage: %~nx0 [options] [backends]
+echo.
+echo Backends:
+echo   onnx        STT/TTS/VAD (ONNX Runtime + Sherpa-ONNX)
+echo   llamacpp    LLM text generation (GGUF models via llama.cpp)
+echo   all         onnx + llamacpp (default)
+echo.
+echo Options:
+echo   --clean     Clean build directory before building
+echo   --shared    Build shared libraries (default: static)
+echo   --test      Build and run tests
+echo   --help      Show this help message
+echo.
+echo Examples:
+echo   %~nx0                        Build all backends (static)
+echo   %~nx0 --shared               Build all backends (shared)
+echo   %~nx0 llamacpp               Build only LlamaCPP
+echo   %~nx0 --clean --test all     Clean build, all backends, run tests
+exit /b 0
+
+:load_versions
+:: Read VERSIONS file and set variables
+set "VERSIONS_FILE=%ROOT_DIR%\VERSIONS"
+if not exist "%VERSIONS_FILE%" (
+    echo [ERROR] VERSIONS file not found at %VERSIONS_FILE%
+    exit /b 1
+)
+for /f "usebackq tokens=1,* delims==" %%a in ("%VERSIONS_FILE%") do (
+    set "line=%%a"
+    if not "!line:~0,1!"=="#" if not "%%a"=="" (
+        set "%%a=%%b"
+    )
+)
+goto :eof
+
+:find_vs
+:: Try to set up VS environment
+set "VSWHERE=%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere.exe"
+if not exist "%VSWHERE%" exit /b 1
+for /f "usebackq tokens=*" %%i in (`"%VSWHERE%" -latest -property installationPath`) do set "VS_PATH=%%i"
+if not defined VS_PATH exit /b 1
+if exist "%VS_PATH%\VC\Auxiliary\Build\vcvars64.bat" (
+    call "%VS_PATH%\VC\Auxiliary\Build\vcvars64.bat" >nul 2>&1
+    exit /b 0
+)
+exit /b 1
diff --git a/sdk/runanywhere-commons/scripts/windows/download-sherpa-onnx.bat b/sdk/runanywhere-commons/scripts/windows/download-sherpa-onnx.bat
new file mode 100644
index 000000000..d9cf7323e
--- /dev/null
+++ b/sdk/runanywhere-commons/scripts/windows/download-sherpa-onnx.bat
@@ -0,0 +1,146 @@
+@echo off
+setlocal enabledelayedexpansion
+
+:: =============================================================================
+:: download-sherpa-onnx.bat
+:: Download Sherpa-ONNX pre-built binaries for Windows x64
+::
+:: Usage: download-sherpa-onnx.bat [--force]
+::
+:: Options:
+::   --force    Re-download even if already present
+::
+:: Prerequisites:
+::   - curl (included in Windows 10+)
+::   - tar  (included in Windows 10+)
+:: =============================================================================
+
+set "SCRIPT_DIR=%~dp0"
+set "ROOT_DIR=%SCRIPT_DIR%..\.."
+set "DEST_DIR=%ROOT_DIR%\third_party\sherpa-onnx-windows"
+
+:: Load versions
+call :load_versions
+if not defined SHERPA_ONNX_VERSION_WINDOWS set "SHERPA_ONNX_VERSION_WINDOWS=1.12.23"
+set "VERSION=%SHERPA_ONNX_VERSION_WINDOWS%"
+
+:: Parse options
+set "FORCE=0"
+if "%~1"=="--force" set "FORCE=1"
+if "%~1"=="--help" goto :show_help
+if "%~1"=="-h" goto :show_help
+
+:: Check if already downloaded
+if exist "%DEST_DIR%\lib" if "%FORCE%"=="0" (
+    echo [OK] Sherpa-ONNX already downloaded at %DEST_DIR%
+    echo      Use --force to re-download.
+    exit /b 0
+)
+
+:: Determine URL
+set "URL=https://github.com/k2-fsa/sherpa-onnx/releases/download/v%VERSION%/sherpa-onnx-v%VERSION%-win-x64-shared.tar.bz2"
+set "ARCHIVE_NAME=sherpa-onnx-v%VERSION%-win-x64-shared"
+
+echo.
+echo ========================================
+echo  Downloading Sherpa-ONNX for Windows
+echo ========================================
+echo.
+echo  Version:     %VERSION%
+echo  URL:         %URL%
+echo  Destination: %DEST_DIR%
+echo.
+
+:: Clean existing
+if exist "%DEST_DIR%" (
+    echo [CLEAN] Removing existing directory...
+    rmdir /s /q "%DEST_DIR%" 2>nul
+)
+
+:: Create temp dir
+set "TEMP_DL=%TEMP%\sherpa_onnx_dl_%RANDOM%"
+mkdir "%TEMP_DL%" 2>nul
+
+:: Download
+echo [DOWNLOAD] Downloading Sherpa-ONNX v%VERSION%...
+curl -L -o "%TEMP_DL%\sherpa-onnx.tar.bz2" "%URL%"
+if errorlevel 1 (
+    echo [ERROR] Download failed.
+    rmdir /s /q "%TEMP_DL%" 2>nul
+    exit /b 1
+)
+
+:: Extract
+echo [EXTRACT] Extracting archive...
+mkdir "%DEST_DIR%" 2>nul
+tar -xjf "%TEMP_DL%\sherpa-onnx.tar.bz2" -C "%TEMP_DL%"
+if errorlevel 1 (
+    echo [ERROR] Extraction failed.
+    rmdir /s /q "%TEMP_DL%" 2>nul
+    exit /b 1
+)
+
+:: Move contents (strip top-level directory)
+for /d %%d in ("%TEMP_DL%\sherpa-onnx-*") do (
+    xcopy /s /y /q "%%d\*" "%DEST_DIR%\" >nul
+)
+
+:: Download C API headers if missing
+if not exist "%DEST_DIR%\include\sherpa-onnx\c-api\c-api.h" (
+    echo [DOWNLOAD] Downloading C API headers...
+    mkdir "%DEST_DIR%\include\sherpa-onnx\c-api" 2>nul
+    curl -sL "https://raw.githubusercontent.com/k2-fsa/sherpa-onnx/v%VERSION%/sherpa-onnx/c-api/c-api.h" ^
+        -o "%DEST_DIR%\include\sherpa-onnx\c-api\c-api.h"
+)
+
+:: Cleanup temp
+rmdir /s /q "%TEMP_DL%" 2>nul
+
+:: Verify
+echo [VERIFY] Checking installation...
+set "VERIFY_OK=1"
+
+if not exist "%DEST_DIR%\lib" (
+    echo [ERROR] lib directory not found
+    set "VERIFY_OK=0"
+)
+if not exist "%DEST_DIR%\include\sherpa-onnx\c-api\c-api.h" (
+    echo [ERROR] C API header not found
+    set "VERIFY_OK=0"
+)
+
+if "%VERIFY_OK%"=="0" (
+    echo [ERROR] Verification failed.
+    exit /b 1
+)
+
+:: Summary
+echo.
+echo [OK] Sherpa-ONNX v%VERSION% downloaded successfully!
+echo.
+echo  Libraries: %DEST_DIR%\lib\
+dir /b "%DEST_DIR%\lib\*.lib" 2>nul
+dir /b "%DEST_DIR%\lib\*.dll" 2>nul
+echo.
+echo  Headers: %DEST_DIR%\include\
+echo.
+
+exit /b 0
+
+:: =============================================================================
+:: Subroutines
+:: =============================================================================
+
+:show_help
+echo Usage: %~nx0 [--force]
+echo   --force    Re-download even if already present
+exit /b 0
+
+:load_versions
+set "VERSIONS_FILE=%ROOT_DIR%\VERSIONS"
+if not exist "%VERSIONS_FILE%" exit /b 1
+for /f "usebackq tokens=1,* delims==" %%a in ("%VERSIONS_FILE%") do (
+    set "line=%%a"
+    if not "!line:~0,1!"=="#" if not "%%a"=="" set "%%a=%%b"
+)
+goto :eof
diff --git a/sdk/runanywhere-commons/src/backends/llamacpp/CMakeLists.txt b/sdk/runanywhere-commons/src/backends/llamacpp/CMakeLists.txt
index 92f934451..91852006b 100644
--- a/sdk/runanywhere-commons/src/backends/llamacpp/CMakeLists.txt
+++ b/sdk/runanywhere-commons/src/backends/llamacpp/CMakeLists.txt
@@ -87,6 +87,19 @@ elseif(RAC_PLATFORM_LINUX)
         set(GGML_NEON ON CACHE BOOL "" FORCE)
         message(STATUS "Enabling NEON for Linux aarch64")
     endif()
+elseif(RAC_PLATFORM_WINDOWS)
+    # Windows: CPU-only by default, no Metal/CUDA/Vulkan
+    set(GGML_METAL OFF CACHE BOOL "" FORCE)
+    set(GGML_CUDA OFF CACHE BOOL "" FORCE)
+    set(GGML_VULKAN OFF CACHE BOOL "" FORCE)
+    set(GGML_OPENCL OFF CACHE BOOL "" FORCE)
+    set(GGML_HIPBLAS OFF CACHE BOOL "" FORCE)
+    set(GGML_SYCL OFF CACHE BOOL "" FORCE)
+    set(GGML_KOMPUTE OFF CACHE BOOL "" FORCE)
+    set(GGML_RPC OFF CACHE BOOL "" FORCE)
+    set(GGML_OPENMP OFF CACHE BOOL "" FORCE)
+    set(GGML_NATIVE OFF CACHE BOOL "" FORCE)
+    message(STATUS "Configuring llama.cpp for Windows (CPU-only)")
 endif()
 
 set(BUILD_SHARED_LIBS OFF CACHE BOOL "Force static libraries for llama.cpp" FORCE)
@@ -245,6 +258,10 @@ elseif(RAC_PLATFORM_LINUX)
     message(STATUS "Configuring LlamaCPP backend for Linux")
     # Linux-specific link libraries
     target_link_libraries(rac_backend_llamacpp PUBLIC pthread dl)
+
+elseif(RAC_PLATFORM_WINDOWS)
+    message(STATUS "Configuring LlamaCPP backend for Windows")
+    # No extra link libraries needed on Windows (threading is built-in)
 endif()
 
 # =============================================================================
diff --git a/sdk/runanywhere-commons/src/backends/onnx/CMakeLists.txt b/sdk/runanywhere-commons/src/backends/onnx/CMakeLists.txt
index d5aeca964..1646c9d9e 100644
--- a/sdk/runanywhere-commons/src/backends/onnx/CMakeLists.txt
+++ b/sdk/runanywhere-commons/src/backends/onnx/CMakeLists.txt
@@ -166,6 +166,42 @@ elseif(RAC_PLATFORM_LINUX)
     else()
         message(STATUS "Sherpa-ONNX not found. Run: ./scripts/linux/download-sherpa-onnx.sh")
     endif()
+
+elseif(RAC_PLATFORM_WINDOWS)
+    set(SHERPA_ONNX_ROOT "${RUNANYWHERE_COMMONS_ROOT}/third_party/sherpa-onnx-windows")
+
+    if(EXISTS "${SHERPA_ONNX_ROOT}/lib/sherpa-onnx-c-api.lib")
+        set(SHERPA_ONNX_AVAILABLE ON)
+        set(SHERPA_LIB_PATH "${SHERPA_ONNX_ROOT}/lib/sherpa-onnx-c-api.lib")
+        set(SHERPA_DLL_PATH "${SHERPA_ONNX_ROOT}/bin/sherpa-onnx-c-api.dll")
+        set(SHERPA_HEADER_PATH "${SHERPA_ONNX_ROOT}/include")
+
+        add_library(sherpa_onnx SHARED IMPORTED GLOBAL)
+        set_target_properties(sherpa_onnx PROPERTIES
+            IMPORTED_IMPLIB "${SHERPA_LIB_PATH}"
+            IMPORTED_LOCATION "${SHERPA_DLL_PATH}"
+            INTERFACE_INCLUDE_DIRECTORIES "${SHERPA_HEADER_PATH}"
+        )
+
+        # Link supporting libraries if present
+        set(SHERPA_ONNX_DEPS
+            "sherpa-onnx-core" "sherpa-onnx-fst" "sherpa-onnx-fstfar"
+            "sherpa-onnx-kaldifst-core" "kaldi-decoder-core" "kaldi-native-fbank-core"
+            "piper_phonemize" "espeak-ng" "ucd"
+        )
+
+        foreach(dep ${SHERPA_ONNX_DEPS})
+            if(EXISTS "${SHERPA_ONNX_ROOT}/lib/${dep}.lib")
+                add_library(sherpa_${dep} STATIC IMPORTED GLOBAL)
+                set_target_properties(sherpa_${dep} PROPERTIES IMPORTED_LOCATION "${SHERPA_ONNX_ROOT}/lib/${dep}.lib")
+                target_link_libraries(sherpa_onnx INTERFACE sherpa_${dep})
+            endif()
+        endforeach()
+
+        message(STATUS "Found Sherpa-ONNX Windows: ${SHERPA_LIB_PATH}")
+    else()
+        message(STATUS "Sherpa-ONNX not found for Windows at ${SHERPA_ONNX_ROOT}")
+    endif()
 endif()
 
 # =============================================================================
@@ -282,6 +318,10 @@ elseif(RAC_PLATFORM_MACOS)
 
 elseif(RAC_PLATFORM_LINUX)
     target_link_libraries(rac_backend_onnx PUBLIC pthread dl)
+
+elseif(RAC_PLATFORM_WINDOWS)
+    # No extra link libraries needed on Windows
+    message(STATUS "ONNX Backend: CPU EP for Windows")
 endif()
 
 # =============================================================================
diff --git a/sdk/runanywhere-commons/src/backends/onnx/onnx_backend.cpp b/sdk/runanywhere-commons/src/backends/onnx/onnx_backend.cpp
index c8f3310a1..2332c6d93 100644
--- a/sdk/runanywhere-commons/src/backends/onnx/onnx_backend.cpp
+++ b/sdk/runanywhere-commons/src/backends/onnx/onnx_backend.cpp
@@ -14,8 +14,11 @@
 
 #include "onnx_backend.h"
 
-#include <dirent.h>
-#include <sys/stat.h>
+#include "rac/core/rac_platform_compat.h"
+
+#ifdef _WIN32
+#include <direct.h>  // for _mkdir
+#endif
 
 #include <cctype>
 #include <cstdio>
@@ -673,7 +676,11 @@ static void ensure_espeak_voice_files(const std::string& espeak_data_dir) {
     }
 
     if (stat(voices_dir.c_str(), &st) != 0) {
+#ifdef _WIN32
+        int mk = _mkdir(voices_dir.c_str());
+#else
         int mk = mkdir(voices_dir.c_str(), 0755);
+#endif
         RAC_LOG_INFO("ONNX.TTS", "[ensure_voices] Created voices/ dir: result=%d errno=%d", mk, errno);
     } else {
         RAC_LOG_INFO("ONNX.TTS", "[ensure_voices] voices/ dir already exists");
diff --git a/sdk/runanywhere-commons/src/backends/onnx/wakeword_onnx.cpp b/sdk/runanywhere-commons/src/backends/onnx/wakeword_onnx.cpp
index f0350b434..a62ebca32 100644
--- a/sdk/runanywhere-commons/src/backends/onnx/wakeword_onnx.cpp
+++ b/sdk/runanywhere-commons/src/backends/onnx/wakeword_onnx.cpp
@@ -19,6 +19,7 @@
 #include "rac/backends/rac_wakeword_onnx.h"
 #include "rac/backends/rac_vad_onnx.h"
 #include "rac/core/rac_logger.h"
+#include "rac/core/rac_platform_compat.h"
 
 #ifdef RAC_HAS_ONNX
 #include <onnxruntime_cxx_api.h>
@@ -567,7 +568,7 @@ RAC_ONNX_API rac_result_t rac_wakeword_onnx_init_shared_models(
         // Load melspectrogram model (required for proper pipeline)
         if (melspec_model_path) {
             backend->melspec_session = std::make_unique<Ort::Session>(
-                *backend->env, melspec_model_path, *backend->session_options);
+                *backend->env, RAC_ORT_PATH(melspec_model_path), *backend->session_options);
 
             // Get input/output names
             auto input_name = backend->melspec_session->GetInputNameAllocated(0, backend->allocator);
@@ -584,7 +585,7 @@ RAC_ONNX_API rac_result_t rac_wakeword_onnx_init_shared_models(
         // Load embedding model (required)
         if (embedding_model_path) {
             backend->embedding_session = std::make_unique<Ort::Session>(
-                *backend->env, embedding_model_path, *backend->session_options);
+                *backend->env, RAC_ORT_PATH(embedding_model_path), *backend->session_options);
 
             // Get input/output names
             auto input_name = backend->embedding_session->GetInputNameAllocated(0, backend->allocator);
@@ -651,7 +652,7 @@ RAC_ONNX_API rac_result_t rac_wakeword_onnx_load_model(
         model.threshold = backend->global_threshold;
 
         model.session = std::make_unique<Ort::Session>(
-            *backend->env, model_path, *backend->session_options);
+            *backend->env, RAC_ORT_PATH(model_path), *backend->session_options);
 
         // Get input/output names
         auto input_name = model.session->GetInputNameAllocated(0, backend->allocator);
diff --git a/sdk/runanywhere-commons/src/backends/whispercpp/CMakeLists.txt b/sdk/runanywhere-commons/src/backends/whispercpp/CMakeLists.txt
index 84a5dcee3..dad3aad0b 100644
--- a/sdk/runanywhere-commons/src/backends/whispercpp/CMakeLists.txt
+++ b/sdk/runanywhere-commons/src/backends/whispercpp/CMakeLists.txt
@@ -70,6 +70,14 @@ elseif(RAC_PLATFORM_MACOS)
     set(GGML_METAL ON CACHE BOOL "" FORCE)
     set(GGML_ACCELERATE ON CACHE BOOL "" FORCE)
     set(GGML_METAL_EMBED_LIBRARY ON CACHE BOOL "" FORCE)
+elseif(RAC_PLATFORM_WINDOWS)
+    set(GGML_METAL OFF CACHE BOOL "" FORCE)
+    set(GGML_CUDA OFF CACHE BOOL "" FORCE)
+    set(GGML_VULKAN OFF CACHE BOOL "" FORCE)
+    set(GGML_OPENCL OFF CACHE BOOL "" FORCE)
+    set(GGML_OPENMP OFF CACHE BOOL "" FORCE)
+    set(GGML_NATIVE OFF CACHE BOOL "" FORCE)
+    message(STATUS "Configuring whisper.cpp for Windows (CPU-only)")
 endif()
 
 set(BUILD_SHARED_LIBS OFF CACHE BOOL "Force static libraries for whisper.cpp" FORCE)
@@ -154,6 +162,10 @@ elseif(RAC_PLATFORM_MACOS)
         "-framework Metal"
         "-framework MetalKit"
     )
+
+elseif(RAC_PLATFORM_WINDOWS)
+    message(STATUS "Configuring WhisperCPP backend for Windows")
+    # No extra link libraries needed on Windows
 endif()
 
 # =============================================================================
diff --git a/sdk/runanywhere-commons/src/core/rac_structured_error.cpp b/sdk/runanywhere-commons/src/core/rac_structured_error.cpp
index 67d34c510..07ebcd88d 100644
--- a/sdk/runanywhere-commons/src/core/rac_structured_error.cpp
+++ b/sdk/runanywhere-commons/src/core/rac_structured_error.cpp
@@ -18,6 +18,9 @@
 #if defined(__APPLE__) || defined(__linux__)
 #include <execinfo.h>
 #endif
+#if defined(_WIN32)
+#include <windows.h>
+#endif
 
 // =============================================================================
 // THREAD-LOCAL STORAGE
@@ -226,6 +229,21 @@ int32_t rac_error_capture_stack_trace(rac_error_t* error) {
         free(symbols);
     }
 
+    return captured;
+#elif defined(_WIN32)
+    void* buffer[RAC_MAX_STACK_FRAMES];
+    USHORT frame_count = CaptureStackBackTrace(2, RAC_MAX_STACK_FRAMES, buffer, NULL);
+
+    int captured = 0;
+    for (USHORT i = 0; i < frame_count && captured < RAC_MAX_STACK_FRAMES; i++) {
+        error->stack_frames[captured].address = buffer[i];
+        error->stack_frames[captured].function = nullptr;
+        error->stack_frames[captured].file = nullptr;
+        error->stack_frames[captured].line = 0;
+        captured++;
+    }
+
+    error->stack_frame_count = captured;
     return captured;
 #else
     // Platform doesn't support backtrace (Android, Windows, etc.)
diff --git a/sdk/runanywhere-commons/src/features/rag/CMakeLists.txt b/sdk/runanywhere-commons/src/features/rag/CMakeLists.txt
index 1e943c26a..defc1bd85 100644
--- a/sdk/runanywhere-commons/src/features/rag/CMakeLists.txt
+++ b/sdk/runanywhere-commons/src/features/rag/CMakeLists.txt
@@ -103,6 +103,7 @@ set_target_properties(rac_backend_rag PROPERTIES
 target_compile_options(rac_backend_rag PRIVATE
     $<$<CXX_COMPILER_ID:GNU,Clang,AppleClang>:-Wno-unused-parameter>
     $<$<CXX_COMPILER_ID:GNU,Clang,AppleClang>:-Wno-missing-field-initializers>
+    $<$<CXX_COMPILER_ID:MSVC>:/wd4244 /wd4267 /wd4996>
 )
 
 target_compile_definitions(rac_backend_rag PRIVATE
diff --git a/sdk/runanywhere-commons/src/features/rag/onnx_embedding_provider.cpp b/sdk/runanywhere-commons/src/features/rag/onnx_embedding_provider.cpp
index 85ac2475c..79ff80904 100644
--- a/sdk/runanywhere-commons/src/features/rag/onnx_embedding_provider.cpp
+++ b/sdk/runanywhere-commons/src/features/rag/onnx_embedding_provider.cpp
@@ -1007,12 +1007,23 @@ class ONNXEmbeddingProvider::Impl {
         }
 
         // Load model with session options
+#ifdef _WIN32
+        // ONNX Runtime on Windows requires wchar_t* paths
+        std::wstring wpath(model_path.begin(), model_path.end());
+        status_guard.reset(ort_api_->CreateSession(
+            ort_env_,
+            wpath.c_str(),
+            options_guard.get(),
+            &session_
+        ));
+#else
         status_guard.reset(ort_api_->CreateSession(
             ort_env_,
             model_path.c_str(),
             options_guard.get(),
             &session_
         ));
+#endif
         // options_guard automatically releases session options on scope exit
 
         if (status_guard.is_error()) {
diff --git a/sdk/runanywhere-commons/src/features/rag/rag_backend.h b/sdk/runanywhere-commons/src/features/rag/rag_backend.h
index 05775c25d..6d74962e1 100644
--- a/sdk/runanywhere-commons/src/features/rag/rag_backend.h
+++ b/sdk/runanywhere-commons/src/features/rag/rag_backend.h
@@ -44,7 +44,11 @@ struct RAGBackendConfig {
  * Coordinates vector store, embeddings service, and LLM service for
  * retrieval-augmented generation. Thread-safe for all operations.
  */
+#if defined(_MSC_VER)
+class RAGBackend {
+#else
 class __attribute__((visibility("default"))) RAGBackend {
+#endif
 public:
     /**
      * @brief Construct RAG pipeline with service handles
diff --git a/sdk/runanywhere-commons/src/features/result_free.cpp b/sdk/runanywhere-commons/src/features/result_free.cpp
index 241ddffe3..f47f55da9 100644
--- a/sdk/runanywhere-commons/src/features/result_free.cpp
+++ b/sdk/runanywhere-commons/src/features/result_free.cpp
@@ -13,9 +13,17 @@
 #include "rac/features/tts/rac_tts_types.h"
 #include "rac/features/embeddings/rac_embeddings_types.h"
 
+// MSVC does not support __attribute__((weak)).
+// Use /alternatename linker directive for weak symbol emulation on MSVC.
+#ifdef _MSC_VER
+#define RAC_WEAK_SYMBOL
+#else
+#define RAC_WEAK_SYMBOL __attribute__((weak))
+#endif
+
 extern "C" {
 
-__attribute__((weak)) void rac_llm_result_free(rac_llm_result_t* result) {
+RAC_WEAK_SYMBOL void rac_llm_result_free(rac_llm_result_t* result) {
     if (result) {
         if (result->text) {
             free(const_cast<char*>(result->text));
@@ -24,7 +32,7 @@ __attribute__((weak)) void rac_llm_result_free(rac_llm_result_t* result) {
     }
 }
 
-__attribute__((weak)) void rac_stt_result_free(rac_stt_result_t* result) {
+RAC_WEAK_SYMBOL void rac_stt_result_free(rac_stt_result_t* result) {
     if (result) {
         if (result->text) {
             free(const_cast<char*>(result->text));
@@ -48,7 +56,7 @@ __attribute__((weak)) void rac_stt_result_free(rac_stt_result_t* result) {
     }
 }
 
-__attribute__((weak)) void rac_tts_result_free(rac_tts_result_t* result) {
+RAC_WEAK_SYMBOL void rac_tts_result_free(rac_tts_result_t* result) {
     if (result) {
         if (result->audio_data) {
             free(result->audio_data);
@@ -58,7 +66,7 @@ __attribute__((weak)) void rac_tts_result_free(rac_tts_result_t* result) {
     }
 }
 
-__attribute__((weak)) void rac_embeddings_result_free(rac_embeddings_result_t* result) {
+RAC_WEAK_SYMBOL void rac_embeddings_result_free(rac_embeddings_result_t* result) {
     if (result) {
         if (result->embeddings) {
             for (size_t i = 0; i < result->num_embeddings; i++) {
diff --git a/sdk/runanywhere-commons/src/features/vlm/vlm_component.cpp b/sdk/runanywhere-commons/src/features/vlm/vlm_component.cpp
index 2bc804233..04084adec 100644
--- a/sdk/runanywhere-commons/src/features/vlm/vlm_component.cpp
+++ b/sdk/runanywhere-commons/src/features/vlm/vlm_component.cpp
@@ -9,11 +9,10 @@
 #include <chrono>
 #include <cstdlib>
 #include <cstring>
-#include <dirent.h>
 #include <mutex>
 #include <random>
 #include <string>
-#include <sys/stat.h>
+#include "rac/core/rac_platform_compat.h"
 
 #include "rac/core/capabilities/rac_lifecycle.h"
 #include "rac/core/rac_core.h"
diff --git a/sdk/runanywhere-commons/src/infrastructure/download/download_orchestrator.cpp b/sdk/runanywhere-commons/src/infrastructure/download/download_orchestrator.cpp
index b8cbebb63..f52b0646f 100644
--- a/sdk/runanywhere-commons/src/infrastructure/download/download_orchestrator.cpp
+++ b/sdk/runanywhere-commons/src/infrastructure/download/download_orchestrator.cpp
@@ -18,12 +18,15 @@
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
-#include <dirent.h>
 #include <memory>
 #include <mutex>
 #include <string>
-#include <sys/stat.h>
 #include <vector>
+#include "rac/core/rac_platform_compat.h"
+
+#ifdef _WIN32
+#include <direct.h>  // for _mkdir
+#endif
 
 #include "rac/core/rac_logger.h"
 #include "rac/core/rac_platform_adapter.h"
@@ -147,10 +150,18 @@ static bool mkdir_p(const char* path) {
     while ((pos = s.find('/', pos + 1)) != std::string::npos) {
         std::string sub = s.substr(0, pos);
         if (!sub.empty()) {
+#ifdef _WIN32
+            _mkdir(sub.c_str());
+#else
             mkdir(sub.c_str(), 0755);
+#endif
         }
     }
+#ifdef _WIN32
+    return _mkdir(s.c_str()) == 0 || dir_exists(path);
+#else
     return mkdir(s.c_str(), 0755) == 0 || dir_exists(path);
+#endif
 }
 
 /**
diff --git a/sdk/runanywhere-commons/src/infrastructure/extraction/rac_extraction.cpp b/sdk/runanywhere-commons/src/infrastructure/extraction/rac_extraction.cpp
index daed9a0dd..cb6e5fea9 100644
--- a/sdk/runanywhere-commons/src/infrastructure/extraction/rac_extraction.cpp
+++ b/sdk/runanywhere-commons/src/infrastructure/extraction/rac_extraction.cpp
@@ -15,8 +15,7 @@
 #include <cstdio>
 #include <cstring>
 #include <string>
-#include <sys/stat.h>
-#include <sys/types.h>
+#include "rac/core/rac_platform_compat.h"
 
 #ifdef _WIN32
 #include <direct.h>  // for _mkdir
diff --git a/sdk/runanywhere-commons/src/infrastructure/telemetry/telemetry_json.cpp b/sdk/runanywhere-commons/src/infrastructure/telemetry/telemetry_json.cpp
index fab9ec8d6..65d34cd3b 100644
--- a/sdk/runanywhere-commons/src/infrastructure/telemetry/telemetry_json.cpp
+++ b/sdk/runanywhere-commons/src/infrastructure/telemetry/telemetry_json.cpp
@@ -124,7 +124,11 @@ class JsonBuilder {
         time_t secs = ms / 1000;
         int millis = ms % 1000;
         struct tm tm_info;
+#ifdef _WIN32
+        gmtime_s(&tm_info, &secs);
+#else
         gmtime_r(&secs, &tm_info);
+#endif
 
         char buf[32];
         strftime(buf, sizeof(buf), "%Y-%m-%dT%H:%M:%S", &tm_info);
diff --git a/sdk/runanywhere-commons/tests/CMakeLists.txt b/sdk/runanywhere-commons/tests/CMakeLists.txt
index 6ddd981ba..77e49b104 100644
--- a/sdk/runanywhere-commons/tests/CMakeLists.txt
+++ b/sdk/runanywhere-commons/tests/CMakeLists.txt
@@ -4,6 +4,20 @@ cmake_minimum_required(VERSION 3.22)
 # Integration Test Suite for runanywhere-commons
 # =============================================================================
 
+# Helper: link bundled archive dependencies to test targets on MSVC.
+# On MSVC, transitive static lib deps from archive_static don't propagate fully.
+function(rac_link_archive_deps target)
+    if(TARGET archive_static)
+        target_link_libraries(${target} PRIVATE archive_static)
+    endif()
+    if(TARGET zlibstatic)
+        target_link_libraries(${target} PRIVATE zlibstatic)
+    endif()
+    if(TARGET bz2_bundled)
+        target_link_libraries(${target} PRIVATE bz2_bundled)
+    endif()
+endfunction()
+
 # --- test_core: Always built (no backend dependency) ---
 add_executable(test_core test_core.cpp)
 target_include_directories(test_core PRIVATE
@@ -11,29 +25,29 @@ target_include_directories(test_core PRIVATE
     ${CMAKE_SOURCE_DIR}/include
 )
 target_link_libraries(test_core PRIVATE rac_commons)
+rac_link_archive_deps(test_core)
 target_compile_features(test_core PRIVATE cxx_std_20)
 add_test(NAME core_tests COMMAND test_core --run-all)
 
 # --- test_extraction: Always built (no backend dependency) ---
-# Tests rac_extract_archive_native() and rac_detect_archive_type() from libarchive.
 add_executable(test_extraction test_extraction.cpp)
 target_include_directories(test_extraction PRIVATE
     ${CMAKE_CURRENT_SOURCE_DIR}
     ${CMAKE_SOURCE_DIR}/include
 )
 target_link_libraries(test_extraction PRIVATE rac_commons)
+rac_link_archive_deps(test_extraction)
 target_compile_features(test_extraction PRIVATE cxx_std_17)
 add_test(NAME extraction_tests COMMAND test_extraction --run-all)
 
 # --- test_download_orchestrator: Always built (no backend dependency) ---
-# Tests rac_find_model_path_after_extraction(), rac_download_compute_destination(),
-# and rac_download_requires_extraction() from rac_download_orchestrator.h.
 add_executable(test_download_orchestrator test_download_orchestrator.cpp)
 target_include_directories(test_download_orchestrator PRIVATE
     ${CMAKE_CURRENT_SOURCE_DIR}
     ${CMAKE_SOURCE_DIR}/include
 )
 target_link_libraries(test_download_orchestrator PRIVATE rac_commons)
+rac_link_archive_deps(test_download_orchestrator)
 target_compile_features(test_download_orchestrator PRIVATE cxx_std_17)
 add_test(NAME download_orchestrator_tests COMMAND test_download_orchestrator --run-all)
 
@@ -132,11 +146,29 @@ if(UNIX AND NOT APPLE)
     endforeach()
 endif()
 
+# --- Windows: Copy DLLs to test output directory ---
+if(WIN32)
+    set(ONNX_WIN_BIN_DIR "${CMAKE_SOURCE_DIR}/third_party/onnxruntime-windows/bin")
+    set(SHERPA_WIN_BIN_DIR "${CMAKE_SOURCE_DIR}/third_party/sherpa-onnx-windows/bin")
+    foreach(test_target test_vad test_stt test_tts test_wakeword test_voice_agent)
+        if(TARGET ${test_target})
+            # Copy ONNX Runtime DLL if present
+            if(EXISTS "${onnxruntime_SOURCE_DIR}/lib/onnxruntime.dll")
+                add_custom_command(TARGET ${test_target} POST_BUILD
+                    COMMAND ${CMAKE_COMMAND} -E copy_if_different
+                        "${onnxruntime_SOURCE_DIR}/lib/onnxruntime.dll"
+                        $<TARGET_FILE_DIR:${test_target}>
+                )
+            endif()
+        endif()
+    endforeach()
+endif()
+
 # =============================================================================
 # RAG Pipeline Tests (GoogleTest)
 # =============================================================================
 
-if(RAC_BACKEND_RAG)
+if(RAC_BUILD_BACKENDS AND RAC_BACKEND_RAG AND NOT (WIN32 AND RAC_BUILD_SHARED))
     include(FetchContent)
     find_package(Threads REQUIRED)
 
@@ -149,11 +181,16 @@ if(RAC_BACKEND_RAG)
     )
     set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
     FetchContent_MakeAvailable(googletest)
+    include(GoogleTest)
 
-    # RAG pipeline thread safety test
+    # RAG pipeline thread safety test (disabled on Windows — needs IEmbeddingProvider internal header)
+    if(NOT WIN32)
     add_executable(rac_rag_backend_thread_safety_test
         rag_backend_thread_safety_test.cpp
     )
+    target_include_directories(rac_rag_backend_thread_safety_test PRIVATE
+        ${CMAKE_SOURCE_DIR}/src/features/rag
+    )
     target_link_libraries(rac_rag_backend_thread_safety_test
         PRIVATE
         rac_commons
@@ -161,7 +198,6 @@ if(RAC_BACKEND_RAG)
         GTest::gtest_main
     )
     target_compile_features(rac_rag_backend_thread_safety_test PRIVATE cxx_std_20)
-    include(GoogleTest)
     gtest_discover_tests(rac_rag_backend_thread_safety_test
         DISCOVERY_MODE PRE_TEST
     )
@@ -169,11 +205,15 @@ if(RAC_BACKEND_RAG)
         NAME rac_rag_backend_thread_safety_test
         COMMAND rac_rag_backend_thread_safety_test
     )
+    endif()
 
     # Chunker Unit Tests
     add_executable(rac_chunker_test
         chunker_test.cpp
     )
+    target_include_directories(rac_chunker_test PRIVATE
+        ${CMAKE_SOURCE_DIR}/src/features/rag
+    )
     target_link_libraries(rac_chunker_test
         PRIVATE
         rac_commons
diff --git a/sdk/runanywhere-commons/tests/test_common.h b/sdk/runanywhere-commons/tests/test_common.h
index 748ef9513..d37fac566 100644
--- a/sdk/runanywhere-commons/tests/test_common.h
+++ b/sdk/runanywhere-commons/tests/test_common.h
@@ -1,6 +1,13 @@
 #ifndef TEST_COMMON_H
 #define TEST_COMMON_H
 
+// Ensure M_PI is defined on MSVC (requires _USE_MATH_DEFINES before <cmath>)
+#ifdef _MSC_VER
+#ifndef _USE_MATH_DEFINES
+#define _USE_MATH_DEFINES
+#endif
+#endif
+
 #include <algorithm>
 #include <chrono>
 #include <cmath>
diff --git a/sdk/runanywhere-commons/tests/test_config.h b/sdk/runanywhere-commons/tests/test_config.h
index 5dab8ca11..296c00ff4 100644
--- a/sdk/runanywhere-commons/tests/test_config.h
+++ b/sdk/runanywhere-commons/tests/test_config.h
@@ -4,7 +4,20 @@
 #include <climits>
 #include <cstdlib>
 #include <string>
-#include <sys/stat.h>
+#include "rac/core/rac_platform_compat.h"
+
+#ifdef _WIN32
+#include <windows.h>
+#ifndef PATH_MAX
+#define PATH_MAX MAX_PATH
+#endif
+// realpath equivalent on Windows
+static inline char* realpath(const char* path, char* resolved) {
+    return _fullpath(resolved, path, PATH_MAX);
+}
+#else
+#include <unistd.h>
+#endif
 
 #include "test_common.h"
 
diff --git a/sdk/runanywhere-commons/tests/test_download_orchestrator.cpp b/sdk/runanywhere-commons/tests/test_download_orchestrator.cpp
index 614802595..3a6dc026d 100644
--- a/sdk/runanywhere-commons/tests/test_download_orchestrator.cpp
+++ b/sdk/runanywhere-commons/tests/test_download_orchestrator.cpp
@@ -19,8 +19,17 @@
 #include <cstring>
 #include <fstream>
 #include <string>
-#include <sys/stat.h>
+#include "rac/core/rac_platform_compat.h"
+
+#ifdef _WIN32
+#include <direct.h>
+#include <io.h>
+#include <process.h>
+#include <windows.h>
+#define getpid _getpid
+#else
 #include <unistd.h>
+#endif
 
 // =============================================================================
 // Test helpers
@@ -28,6 +37,14 @@
 
 /** Create a unique temporary directory for test artifacts. */
 static std::string create_temp_dir(const std::string& suffix) {
+#ifdef _WIN32
+    char tmp_path[MAX_PATH];
+    GetTempPathA(MAX_PATH, tmp_path);
+    char tmp_dir[MAX_PATH];
+    snprintf(tmp_dir, sizeof(tmp_dir), "%srac_dl_test_%s_%d", tmp_path, suffix.c_str(), getpid());
+    _mkdir(tmp_dir);
+    return std::string(tmp_dir);
+#else
     char tmpl[256];
     snprintf(tmpl, sizeof(tmpl), "/tmp/rac_dl_test_%s_XXXXXX", suffix.c_str());
     char* result = mkdtemp(tmpl);
@@ -36,11 +53,16 @@ static std::string create_temp_dir(const std::string& suffix) {
         return "";
     }
     return std::string(result);
+#endif
 }
 
 /** Recursively remove a directory. */
 static void remove_dir(const std::string& path) {
+#ifdef _WIN32
+    std::string cmd = "rmdir /s /q \"" + path + "\" 2>nul";
+#else
     std::string cmd = "rm -rf \"" + path + "\"";
+#endif
     system(cmd.c_str());
 }
 
diff --git a/sdk/runanywhere-commons/tests/test_extraction.cpp b/sdk/runanywhere-commons/tests/test_extraction.cpp
index bc62fc87a..0b2c2f370 100644
--- a/sdk/runanywhere-commons/tests/test_extraction.cpp
+++ b/sdk/runanywhere-commons/tests/test_extraction.cpp
@@ -19,12 +19,30 @@
 #include <cstring>
 #include <fstream>
 #include <string>
-#include <sys/stat.h>
-#include <unistd.h>
+#include "rac/core/rac_platform_compat.h"
 #include <vector>
 
+#ifdef _WIN32
+#include <direct.h>
+#include <io.h>
+#include <process.h>
+#include <windows.h>
+#define getpid _getpid
+#else
+#include <unistd.h>
+#endif
+
 // No platform adapter or rac_init() needed — extraction APIs are standalone.
 
+// Portable mkdir wrapper
+static inline int compat_mkdir(const char* path) {
+#ifdef _WIN32
+    return _mkdir(path);
+#else
+    return compat_mkdir(path);
+#endif
+}
+
 // =============================================================================
 // Test helpers
 // =============================================================================
@@ -33,6 +51,14 @@ static std::string g_test_dir;
 
 /** Create a unique temporary directory for test artifacts. */
 static std::string create_temp_dir(const std::string& suffix) {
+#ifdef _WIN32
+    char tmp_path[MAX_PATH];
+    GetTempPathA(MAX_PATH, tmp_path);
+    char tmp_dir[MAX_PATH];
+    snprintf(tmp_dir, sizeof(tmp_dir), "%srac_test_%s_%d", tmp_path, suffix.c_str(), _getpid());
+    _mkdir(tmp_dir);
+    return std::string(tmp_dir);
+#else
     char tmpl[256];
     snprintf(tmpl, sizeof(tmpl), "/tmp/rac_test_%s_XXXXXX", suffix.c_str());
     char* result = mkdtemp(tmpl);
@@ -41,6 +67,7 @@ static std::string create_temp_dir(const std::string& suffix) {
         return "";
     }
     return std::string(result);
+#endif
 }
 
 /** Recursively remove a directory. */
@@ -93,8 +120,8 @@ static bool has_zip() {
 static std::string create_test_tar_gz(const std::string& base_dir) {
     std::string content_dir = base_dir + "/content";
     std::string sub_dir = content_dir + "/subdir";
-    mkdir(content_dir.c_str(), 0755);
-    mkdir(sub_dir.c_str(), 0755);
+    compat_mkdir(content_dir.c_str());
+    compat_mkdir(sub_dir.c_str());
 
     write_file(content_dir + "/hello.txt", "Hello, World!\n");
     write_file(content_dir + "/data.bin", std::string(256, '\x42'));
@@ -113,8 +140,8 @@ static std::string create_test_tar_gz(const std::string& base_dir) {
 static std::string create_test_zip(const std::string& base_dir) {
     std::string content_dir = base_dir + "/zipcontent";
     std::string sub_dir = content_dir + "/subdir";
-    mkdir(content_dir.c_str(), 0755);
-    mkdir(sub_dir.c_str(), 0755);
+    compat_mkdir(content_dir.c_str());
+    compat_mkdir(sub_dir.c_str());
 
     write_file(content_dir + "/readme.txt", "ZIP test file\n");
     write_file(content_dir + "/binary.dat", std::string(128, '\xAB'));
@@ -565,8 +592,8 @@ static TestResult test_default_options_skip_macos() {
     std::string archive_dir = create_temp_dir("macos_src");
     std::string content_dir = archive_dir + "/macos_content";
     std::string macosx_dir = content_dir + "/__MACOSX";
-    mkdir(content_dir.c_str(), 0755);
-    mkdir(macosx_dir.c_str(), 0755);
+    compat_mkdir(content_dir.c_str());
+    compat_mkdir(macosx_dir.c_str());
 
     write_file(content_dir + "/real_file.txt", "real content\n");
     write_file(content_dir + "/._resource_fork", "resource fork\n");
@@ -618,8 +645,8 @@ static TestResult test_custom_options_keep_macos() {
     std::string archive_dir = create_temp_dir("keepmac_src");
     std::string content_dir = archive_dir + "/keep_content";
     std::string macosx_dir = content_dir + "/__MACOSX";
-    mkdir(content_dir.c_str(), 0755);
-    mkdir(macosx_dir.c_str(), 0755);
+    compat_mkdir(content_dir.c_str());
+    compat_mkdir(macosx_dir.c_str());
 
     write_file(content_dir + "/file.txt", "content\n");
     write_file(macosx_dir + "/meta.plist", "metadata\n");