OpenAI
GPT-5.3 Codex
Announced Feb 5, 2026
Coding agents you can steer while they work
01
What could it do?
OpenAI combined coding with reasoning and professional computer tasks.
02
What changed?
Users could interact with Codex during longer tasks without restarting the work.
WHY IT MATTERED
Moved coding assistance toward a more continuous collaboration.
03
Where it fell short
Use in its own development was assistance to engineers, not autonomous self creation.
Sources checked Oct 7, 2026
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
156.8index points
Tested variant: GPT-5.3 CodexSource interval: 152.8 to 160.7Variant date in source: Feb 5, 2026A 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 4.0