diff --git a/fuzzing/CMakeLists.txt b/fuzzing/CMakeLists.txt
index 412c51bc..cf41d602 100644
--- a/fuzzing/CMakeLists.txt
+++ b/fuzzing/CMakeLists.txt
@@ -89,4 +89,11 @@ add_executable(fuzz_evm_payload
     ../src/evm_parser.c
 )
 target_compile_definitions(fuzz_evm_payload PRIVATE NO_BOLOS_SDK=1)
-target_link_libraries(fuzz_evm_payload mock_bolos)
\ No newline at end of file
+target_link_libraries(fuzz_evm_payload mock_bolos)
+
+add_executable(fuzz_swap_token_utils
+    fuzzer_swap_token_utils.c
+    ../src/swap/swap_token_utils.c
+)
+target_compile_definitions(fuzz_swap_token_utils PRIVATE NO_BOLOS_SDK=1)
+target_link_libraries(fuzz_swap_token_utils mock_bolos)
\ No newline at end of file
diff --git a/fuzzing/fuzzer_swap_token_utils.c b/fuzzing/fuzzer_swap_token_utils.c
new file mode 100644
index 00000000..c0cbeda0
--- /dev/null
+++ b/fuzzing/fuzzer_swap_token_utils.c
@@ -0,0 +1,67 @@
+#include <stdint.h>
+#include <stddef.h>
+#include <string.h>
+
+#include "swap/swap_token_utils.h"
+
+#define MAX_ASSET_LEN 16
+#define MAX_OUT_LEN 64
+#define MAX_STR_LEN 16
+
+static size_t min_size(size_t a, size_t b) {
+    return (a < b) ? a : b;
+}
+
+static uint64_t load_u64_be(const uint8_t *data, size_t len) {
+    uint64_t v = 0;
+    for (size_t i = 0; i < len; i++) {
+        v = (v << 8) | data[i];
+    }
+    return v;
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+    if (data == NULL || size == 0) return 0;
+
+    size_t offset = 0;
+    uint8_t flags = data[offset++];
+
+    uint8_t decimals = (offset < size) ? data[offset++] : 0;
+
+    size_t amount_len = min_size(8, size - offset);
+    uint64_t amount = load_u64_be(data + offset, amount_len);
+    offset += amount_len;
+
+    uint8_t out_len_hint = (offset < size) ? data[offset++] : 0;
+    size_t out_len = out_len_hint % (MAX_OUT_LEN + 1);
+
+    const char *asset = NULL;
+    char asset_buf[MAX_ASSET_LEN + 1];
+    if ((flags & 0x1) && offset < size) {
+        size_t asset_len = data[offset++] % (MAX_ASSET_LEN + 1);
+        size_t avail = size - offset;
+        if (asset_len > avail) asset_len = avail;
+        memcpy(asset_buf, data + offset, asset_len);
+        asset_buf[asset_len] = '\0';
+        asset = asset_buf;
+        offset += asset_len;
+    }
+
+    char out_buf[MAX_OUT_LEN + 1];
+    memset(out_buf, 0, sizeof(out_buf));
+    (void)print_token_amount(amount, asset, decimals, out_buf, out_len);
+
+    uint8_t str_buf[MAX_STR_LEN];
+    size_t str_len = min_size(MAX_STR_LEN, size - offset);
+    memset(str_buf, 0, sizeof(str_buf));
+    if (str_len > 0) {
+        memcpy(str_buf, data + offset, str_len);
+    }
+
+    uint64_t parsed = 0;
+    size_t len_hint = data[0] % (MAX_STR_LEN + 1);
+    (void)swap_str_to_u64(str_buf, len_hint, &parsed);
+    (void)swap_str_to_u64(str_buf, MAX_STR_LEN, &parsed);
+
+    return 0;
+}
\ No newline at end of file
diff --git a/fuzzing/run_fuzzing.sh b/fuzzing/run_fuzzing.sh
index ea55c275..b59d4328 100755
--- a/fuzzing/run_fuzzing.sh
+++ b/fuzzing/run_fuzzing.sh
@@ -61,7 +61,8 @@ setup_directories() {
     # Create corpus directories for each fuzzer
     mkdir -p "$CORPUS_DIR/proto_varlen_parser"
     mkdir -p "$CORPUS_DIR/evm_payload"
-    
+    mkdir -p "$CORPUS_DIR/swap_token_utils"
+
     print_status "Directories created"
 }
 
@@ -94,6 +95,9 @@ generate_corpus() {
     # ERC20 transfer selector only
     printf "\xA9\x05\x9C\xBB" > "$CORPUS_DIR/evm_payload/selector.bin"
     # Full calldata: selector + 32-byte address word + 32-byte amount word
+    # swap_token_utils seeds
+    printf "\x01\x08\x00\x00\x00\x00\x00\x00\x00\x01\x20\x04HBAR" > "$CORPUS_DIR/swap_token_utils/hbar_valid.bin"
+    printf "\x00\x00\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\x10" > "$CORPUS_DIR/swap_token_utils/max_valid.bin"
     (
       printf "\xA9\x05\x9C\xBB"
       # address word: 12 zero pad + 20 0x11 bytes
@@ -156,7 +160,7 @@ run_fuzzer() {
 run_all_fuzzers() {
     print_status "Starting fuzzing campaign..."
     
-    local fuzzers=("proto_varlen_parser" "evm_payload")
+    local fuzzers=("proto_varlen_parser" "evm_payload" "swap_token_utils")
     
     for fuzzer in "${fuzzers[@]}"; do
         run_fuzzer "$fuzzer" "$FUZZ_TIME"