Choosing an AI Provider

Modmixer uses an AI model to write your mod. You bring your own access (an API key or an existing AI subscription) and Modmixer connects to it.

Writing a mod is harder than answering questions. The AI has to produce hundreds of lines of code that compile and load into the game. That takes a stronger model than free tiers offer, and more usage than they allow. The free Claude.ai and ChatGPT tiers also only work inside their own websites, so an outside app like Modmixer can't connect to them.

Recommended: OpenRouter + Kimi K2.6

OpenRouter is a pay-as-you-go API gateway. You add credit to your account and pay per request, with no monthly subscription. Kimi K2.6 is currently the best price/performance pick for modding. It's strong at multi-file code generation at a fraction of the cost of Opus or GPT-5.5.

Sign up, add credit, paste your API key into Modmixer.

Using a Claude or ChatGPT subscription

If you already pay for Claude Pro / Max or ChatGPT Plus / Pro, you can use that instead. Modmixer's model picker will show what your plan unlocks.

A note on Claude: Anthropic recently changed their policy, so third-party apps like Modmixer can no longer draw from your included Claude Pro / Max usage. Requests are billed against the more expensive "extra usage" bucket instead. Claude still works in Modmixer, but OpenRouter is cheaper.

Other providers

Modmixer also supports GitHub Copilot, Google Gemini, and Google Antigravity. They appear in the model picker once you sign in. Use them if you already have access.

Still not sure?

Sign up for OpenRouter, add $5 in credit, pick Kimi K2.6.