# GPT-5.1 spotted on Arena

GPT-5.1 is a model from OpenAI, released on 13 Nov 2025. First seen 11 Sep 2026. Catalogues list a 400,000 tokens context window. 13 evidence links.

- Kind: Sighting
- Developer: OpenAI
- Confidence: Confirmed
- First seen: 2026-09-11T21:39:38.120Z
- Model: [GPT-5.1](https://alexgetman.com/models/openai/gpt-5-1/)
- Canonical: https://alexgetman.com/signals/2026/09/11/gpt-5-1/

## Evidence links

- [Arena · leaderboards](https://openai.com/index/gpt-5-1/)
- [VoxelBench · leaderboard](https://voxelbench.ai/leaderboard)
- [OpenCode · discovery](https://opencode.ai/data/openai/gpt-5-1)
- [OpenRouter](https://openrouter.ai/openai/gpt-5.1)
- [Artificial Analysis · benchmarks](https://artificialanalysis.ai/models)
- [OpenRouter](https://openrouter.ai/openai/gpt-5.1:batch)
- [OpenAI · model index](https://developers.openai.com/api/docs/models/gpt-5.1)
- [OpenAI · pricing](https://developers.openai.com/api/docs/pricing)
- [Azure Foundry · lifecycle](https://learn.microsoft.com/en-us/azure/foundry/concepts/model-lifecycle-retirement?view=azureml-api-2)
- [models.dev · catalogue](https://models.dev/#databricks-gpt-5-1)
- [models.dev · catalogue](https://models.dev/#gpt-5-1)
- [models.dev · catalogue](https://models.dev/#gpt-5.1)
- [OpenAI · deprecations](https://platform.openai.com/docs/deprecations)