Use LibreChat with a free AI API

Set it up

1. Add the custom endpoint below to librechat.yaml.
2. Put your key in .env as ZEROLIMITAI_API_KEY.
3. Restart LibreChat and choose “ZeroLimitAI” in the endpoint menu.

endpoints:
  custom:
    - name: "ZeroLimitAI"
      apiKey: "${ZEROLIMITAI_API_KEY}"
      baseURL: "https://www.zerolimitai.com/api/v1"
      models:
        default: ["auto"]
        fetch: false
      titleConvo: true
      titleModel: "auto"
      modelDisplayLabel: "ZeroLimitAI"

ZEROLIMITAI_API_KEY=zlai_your_key_here

Replace zlai_your_key_here with your key. Base URL: https://www.zerolimitai.com/api/v1. LibreChat's own documentation

Good to know

• titleConvo makes one extra call per new conversation to name it. Set it to false to save calls.
• Only free models answer, and never through a provider that may train on your prompts. Context is at least 32K tokens, depending on the model.
• Need more than the free tier? Annual ($49/year) gives 2,000 calls a day and Lifetime ($99 once) 10,000. See plans.

If something goes wrong

401 invalid_key

The key is mistyped, revoked or missing the zlai_ prefix. Create a new one in your dashboard under Developer.

404 Not Found

The base URL must end in /api/v1 (https://www.zerolimitai.com/api/v1). Tools add /chat/completions themselves.

429 daily_limit

Your account used its calls for the day. The limit is per account, not per key, and resets at 00:00 UTC; the X-RateLimit-Remaining header shows what is left.

“Model not found”, or a model name you did not choose in the response

Any model ID is accepted: one we do not serve is routed by ZeroOptimize, and the response header X-ZeroOptimize-Substituted-From says what you asked for. Use “auto”.

Slow first word

Some free models think before answering. Keep streaming on so text appears as soon as it is written; a model that stays silent is replaced automatically.

Full reference: API docs · live status

Other tools

Configs checked against each tool's documentation on 2026-10-02.