Use Roo Code with a free AI API

Set it up

1. Install Roo Code from the VS Code marketplace.
2. In its settings choose the “OpenAI Compatible” provider.
3. Enter the base URL, your key and the model ID below.

Base URL:  https://www.zerolimitai.com/api/v1
API Key:   zlai_your_key_here
Model ID:  auto

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

Good to know

• Function calling is supported, so Roo’s native tool use works; the request is routed to a free model that supports tools.
• 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.