docs: add comparison matrix to README

COMPARISON.md

@@ -0,0 +1,110 @@
+# Comparison Matrix
+
+## Feature Comparison
+
+This document compares **cliproxyapi-plusplus** with similar tools in the OpenAI-compatible proxy and LLM routing space.
+
+| Repository | Purpose | Key Features | Language/Framework | Maturity | Comparison |
+|------------|---------|--------------|-------------------|----------|------------|
+| **cliproxyapi-plusplus (this fork)** | Agent-native multi-provider proxy | Extended providers, OpenAI-compatible, Unified auth | Go | Stable | Plus fork with third-party support |
+| [litellm](https://github.com/BerriAI/litellm) | LLM proxy | 100+ providers, OpenAI-compatible | Python | Stable | Industry standard |
+| [portkey](https://github.com/PortKey-AI/openapi) | LLM gateway | Observability, Retries, Load balancing | Python | Stable | Enterprise-focused |
+| [go-openai-proxy](https://github.com/linjiao/go-openai-proxy) | Simple proxy | Basic routing, OpenAI-compatible | Go | Beta | Minimal alternative |
+| [localai](https://github.com/mudler/LocalAI) | Local LLM proxy | Self-hosted, OpenAI-compatible | Go | Stable | Local models focus |
+| [ollama](https://github.com/ollama/ollama) | Local LLM runner | Local inference, Simple API | Go | Stable | Local model runner |
+| [textgen-webui](https://github.com/oobabooga/text-generation-webui) | WebUI for LLMs | Web interface, Extensions | Python | Stable | Web-based local |
+
+## Detailed Feature Comparison
+
+### Provider Support
+
+| Provider | cliproxyapi++ | LiteLLM | Portkey | LocalAI |
+|----------|--------------|---------|---------|---------|
+| OpenAI | ✅ | ✅ | ✅ | ✅ |
+| Anthropic | ✅ | ✅ | ✅ | ✅ |
+| Google Gemini | ✅ | ✅ | ✅ | ❌ |
+| Azure OpenAI | ✅ | ✅ | ✅ | ✅ |
+| AWS Bedrock | ✅ | ✅ | ✅ | ✅ |
+| Kiro | ✅ | ❌ | ❌ | ❌ |
+| Copilot | ✅ | ❌ | ❌ | ❌ |
+| Local Models | ❌ | ✅ | ✅ | ✅ |
+
+### Security & Rate Limiting
+
+| Feature | cliproxyapi++ | LiteLLM | Portkey | localai |
+|---------|--------------|---------|---------|---------|
+| Rate Limiting | ✅ | ✅ | ✅ | ✅ |
+| Quota Controls | ✅ | ✅ | ✅ | ❌ |
+| Cooldown Periods | ✅ | ❌ | ✅ | ❌ |
+| Auth Flows | ✅ | ✅ | ✅ | ✅ |
+| Secrets Management | ✅ | ✅ | ✅ | ✅ |
+
+### Operations & Observability
+
+| Feature | cliproxyapi++ | LiteLLM | Portkey |
+|---------|--------------|---------|---------|
+| Management API | ✅ | ❌ | ✅ |
+| Diagnostics | ✅ | ❌ | ✅ |
+| Request Logging | ✅ | ✅ | ✅ |
+| Cost Tracking | ✅ | ✅ | ✅ |
+| CI Policy Checks | ✅ | ❌ | ❌ |
+
+## Fork Enhancements
+
+This fork extends the mainline with:
+
+| Feature | Mainline | This Fork |
+|---------|----------|-----------|
+| Third-party Providers | Limited | Extended (Kiro, Copilot, etc.) |
+| Provider Support | Basic | Full (auth, routing, conversion) |
+| Community Contributions | ❌ | ✅ (community-maintained) |
+
+## Unique Value Proposition
+
+cliproxyapi-plusplus provides:
+
+1. **Agent-Native**: Designed for CLI agent integration
+2. **Extended Providers**: Supports Kiro, Copilot, and more
+3. **Unified Auth**: Single auth flow for heterogeneous providers
+4. **Provider-Aware Routing**: Intelligent routing with model conversion
+
+## Architecture
+
+```
+┌─────────────────────────────────────────────────────────────┐
+│                     cliproxyapi-plusplus                     │
+│  ┌──────────────────────────────────────────────────────┐  │
+│  │              OpenAI-Compatible API                    │  │
+│  └──────────────────────────────────────────────────────┘  │
+│              │                    │                       │
+│  ┌───────────▼───┐    ┌──────────▼────────┐              │
+│  │  Auth Layer   │    │  Routing Engine   │              │
+│  └───────────────┘    └──────────────────┘              │
+│              │                    │                       │
+│  ┌───────────┴────────────────────┴────────────────┐     │
+│  │              Translator Layer                   │     │
+│  │         (Provider-specific conversion)          │     │
+│  └────────────────────────────────────────────────┘     │
+│              │            │            │                 │
+│     ┌────────┘            │            └────────┐        │
+│     ▼                     ▼                     ▼        │
+│  OpenAI    Google/Anthropic    Third-party     ...      │
+└─────────────────────────────────────────────────────────────┘
+```
+
+## When to Use What
+
+| Use Case | Recommended Tool |
+|----------|-----------------|
+| Third-party providers (Kiro, Copilot) | cliproxyapi++ |
+| Quick setup, many providers | LiteLLM |
+| Enterprise observability | Portkey |
+| Local model serving | LocalAI, Ollama |
+| Python-based ecosystem | LiteLLM |
+
+## References
+
+- Mainline: [KooshaPari/cliproxyapi-plusplus](https://github.com/kooshapari/cliproxyapi-plusplus)
+- LiteLLM: [BerriAI/litellm](https://github.com/BerriAI/litellm)
+- Portkey: [PortKey-AI/openapi](https://github.com/PortKey-AI/openapi)
+- LocalAI: [mudler/LocalAI](https://github.com/mudler/LocalAI)