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These endpoints mirror the OpenAI API so any tool, SDK, or library built for OpenAI works with Copilot API without modification. Point your existing OpenAI client at http://localhost:4141 and your requests go to GitHub Copilot instead.

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Base URL

http://localhost:4141
Use a different base URL if you started the server with a custom --port.

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Authentication

When you have API keys configured in auth.apiKeys, pass one of the following headers with every request:
HeaderFormat
x-api-keyx-api-key: <key>
AuthorizationAuthorization: Bearer <key>
If auth.apiKeys is empty, the server accepts requests without authentication.

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POST /v1/chat/completions

Creates a model response for a chat conversation in OpenAI Chat Completions format. Compatible with any tool that uses the OpenAI SDK or calls the OpenAI API directly. 
curl http://localhost:4141/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-5.4",
    "messages": [{"role": "user", "content": "Hello!"}],
    "stream": true
  }'

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POST /v1/responses

OpenAI’s most advanced interface for generating model responses (Responses API). Used by Claude Code and OpenCode for complex agent workflows, including multi-turn tool use and session continuations. When useResponsesApiWebSearch is enabled in your config.json (the default), requests that include a web_search tool are forwarded upstream with the tool intact. Set useResponsesApiWebSearch: false to strip web search tools before sending. 
curl http://localhost:4141/v1/responses \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-5.4",
    "input": [{"role": "user", "content": "Explain async/await in JavaScript."}]
  }'

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GET /v1/models

Lists all models available from your Copilot account in OpenAI format. 
curl http://localhost:4141/v1/models
Example response: 
{
  "object": "list",
  "data": [
    { "id": "gpt-5.4", "object": "model" },
    { "id": "gpt-5-mini", "object": "model" },
    { "id": "claude-opus-4-6", "object": "model" }
  ]
}
Actual model availability depends on your GitHub Copilot subscription tier. The list returned reflects what your account can access at the time of the request.

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POST /v1/embeddings

Creates an embedding vector representing the input text. 
curl http://localhost:4141/v1/embeddings \
  -H "Content-Type: application/json" \
  -d '{
    "model": "text-embedding-3-small",
    "input": "The quick brown fox jumps over the lazy dog"
  }'
Example response: 
{
  "object": "list",
  "data": [
    {
      "object": "embedding",
      "index": 0,
      "embedding": [0.0023, -0.0098, ...]
    }
  ],
  "model": "text-embedding-3-small",
  "usage": {
    "prompt_tokens": 9,
    "total_tokens": 9
  }
}