Which LLM has the largest context window?

Grok 4.1 Fast Reasoning from xAI ranks first (context window 2M tokens), followed by Grok 4 Fast Reasoning (2M tokens) and GPT-6 Astra (1.1M tokens). Ranked by context window, largest first. Models with the same window are ordered by their Respan Index score.

How is this ranking made?

Ranked by context window, largest first. Models with the same window are ordered by their Respan Index score. The Respan Index combines published benchmark results, each linked to its source, and is updated as new results come out.

Can I use these models through one API?

Yes. The Respan gateway serves models from every major provider behind one OpenAI-compatible API, with fallbacks when a provider fails.

AI Gateway overview

Models

Specs, pricing, and capabilities for every model on the Respan gateway.

Models

Models

Best LLM for long context

FAQ

Best model for other jobs