Gemini 4 Carbon API Is Free on Respan, No Card Needed

Gemini 4 Carbon, the reasoning model Google opened up on November 10, is free to call on Respan for 48 hours. Respan is an LLM gateway that speaks both the OpenAI and Anthropic APIs. Sign up, create an API key, and you can plug the model into your usual coding tools without adding a card or buying credits.

What you get

• The free route charges $0 for both input and output, with a 1M-token context window that suits large codebases, long-running agents, and hard reasoning tasks.
• The free window lasts 48 hours and ends around 2 PM Pacific on November 12.
• Free calls have hourly and daily usage caps, and each API response shows how much free allowance you have left.
• The regular route without the :free suffix is billed normally, currently at half price: $2 input and $10 output per 1M tokens.

How to use it

1. Sign up on the Respan platform with Google, GitHub, or email, then create a key under API Keys.
2. Set the base URL to https://gateway.respan.ai/v1 and the model to gemini-4-carbon:free. If a tool doesn't recognize that name, try respan/gemini-4-carbon:free or google_gemini_ai/gemini-4-carbon:free.
3. For tools that use the Anthropic API, such as Claude Code, set the base URL to https://gateway.respan.ai/anthropic and keep the :free suffix on the model name.

See the Gemini 4 Carbon page on Respan, the free-access announcement, and the Respan setup guide.