API Reference

Jan's local API server exposes an OpenAI-compatible REST API at http://127.0.0.1:1337. Use it as a drop-in replacement for cloud APIs in any application that supports OpenAI-compatible endpoints.

Supported Endpoints

`GET /v1/models`

Returns a list of all models currently loaded or available in Jan.


curl http://127.0.0.1:1337/v1/models \
  -H "Authorization: Bearer YOUR_API_KEY"


{
  "object": "list",
  "data": [
    { "id": "jan-v3-4b-base-instruct", "object": "model" }
  ]
}

`POST /v1/chat/completions`

OpenAI-compatible chat completions endpoint. Supports streaming, tool calling, and multi-turn conversations.


curl http://127.0.0.1:1337/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "jan-v3-4b-base-instruct",
    "messages": [{"role": "user", "content": "Hello!"}],
    "stream": false
  }'

`POST /v1/messages`

Anthropic-compatible messages endpoint. Jan automatically translates requests to the internal format, so you can use Anthropic SDK clients pointed at your local server.


curl http://127.0.0.1:1337/v1/messages \
  -H "Content-Type: application/json" \
  -H "x-api-key: YOUR_API_KEY" \
  -d '{
    "model": "jan-v3-4b-base-instruct",
    "max_tokens": 1024,
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

OpenAI Responses API (/v1/responses) support is coming soon.

Use With Agents & Integrations

Jan's local API is designed to wire directly into AI agents and coding tools — no cloud account needed.

Claude Code

Point Claude Code at Jan's local server to run Opus, Sonnet, and Haiku tiers on your own hardware.

OpenClaw

Wire OpenClaw to Jan's local API for a fully private autonomous agent — no cloud, no usage fees.

Using with OpenAI SDK

Point the OpenAI SDK at your local server by setting the base URL and API key:


from openai import OpenAI
client = OpenAI(
    base_url="http://127.0.0.1:1337/v1",
    api_key="YOUR_API_KEY"
)
response = client.chat.completions.create(
    model="jan-v3-4b-base-instruct",
    messages=[{"role": "user", "content": "Hello!"}]
)


import OpenAI from "openai";
const client = new OpenAI({
  baseURL: "http://127.0.0.1:1337/v1",
  apiKey: "YOUR_API_KEY",
});

Model Parameters Server Troubleshooting