GPT-5.3 Codex
GPT-5.3 Codex is an API-only (closed weights) language model from OpenAI, released February 5, 2026. The context window is 391K tokens. API price: $1.75 input / $14 output per million tokens.
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Lab
OpenAI
Released
February 5, 2026
Weights
API-only (closed weights)
Parameters
–
Context
391K
Price / M tokens
$1.75 / $14 in / out
Epoch ECI
not yet rated
Benchmark results
| Benchmark (Epoch AI) | Score |
|---|---|
| SWE-bench Verified | 74.8% |
Links
Announcement · Epoch AI benchmarks
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