OpenAI
GPT-5.1 API
Announced Nov 13, 2025
Adjust reasoning to the task
What could it do?
OpenAI released GPT-5.1 in its API for coding and agent workflows.
What changed?
Added adaptive reasoning and a mode without reasoning.
Developers gained finer control over the balance between response time and reasoning.
Where it fell short
This date records the API release, not the earlier ChatGPT rollout.
Release facts were checked against the sources below. Performance claims belong to the developers; we have not independently tested these models.
Developer announcement or release logBenchmark results
A benchmark estimate, not a percentage or capability multiplier. Reasoning settings are not specified in this source table. Historical estimates can change in later snapshots.
Epoch AI methodology ↗Download the source snapshotChecked Oct 7, 2026 · CC BY 4.0One explicitly named variant per release. Scores come from the same Overall snapshot; preliminary entries and reported intervals are preserved. These are current ratings of earlier variants, not their launch day ratings.
Source: Text Arena ↗Download selected resultsChecked Oct 8, 2026