NVIDIA: Nemotron 3 Ultra (free)

Best for

Best for complex reasoning tasks; weak at simple, repetitive queries.

Pricing

Free via OpenRouter (subject to OpenRouter's rate limits)

How to access it

Available via OpenRouter: create a free account at openrouter.ai, generate an API key, then call this model as nvidia/nemotron-3-ultra-550b-a55b:free through the OpenRouter API (or any OpenRouter-compatible app/client).