GPT-5.3-Codex
openai/gpt-5.3-codex-20260224
OpenAI: GPT-5.3-Codex processes text, image, and file inputs to generate text outputs. It has a context length of 400,000 tokens and supports tools and reasoning. The model is priced at $1.75 per million input tokens and $14 per million output tokens.
- tool use
- structured outputs
- reasoning
At a glance
Specifications
What the API gives you
- Context window
- 400K tokens
- Max output
- 128K tokens
- Input price
- $1.75 / 1M tokens
- Output price
- $14 / 1M tokens
- Cache read
- $0.17 / 1M tokens
- Modalities
- text, image, file → text
- Knowledge cutoff
- —
- Released
- Feb 5, 2026
Measured evidence
Public benchmark record
- Design Arena Coding
- 1145 Elo2026-10-21
- Design Arena Full-stack Agent
- 983 Elo2026-10-14
- Design Arena UI
- 1137 Elo2026-10-21
- Design Arena Web-app Agent
- 1032 Elo2026-10-21
- Design Arena Website
- 1163 Elo2026-10-21
- LMArena WebDev
- 1371 Elo2026-10-19
- LMArena WebDev Image-to-Web
- 1443 Elo2026-10-19
LMArena data licensed CC-BY-4.0. Aider (Apache-2.0) and SWE-bench (MIT) are open. Design Arena uses blind human preference.
Task evidence
How broad is the support?
Each status is exact to this model version and the selected task. Official release claims remain provisional.
- Best LLM for Frontend & UIEstablished evidence
91% of intended weighted task evidence across 2 independent sources. 6 of 6 configured evaluation feeds currently have results.
- Best LLM for CodingEstablished evidence
36% of intended weighted task evidence across 2 independent sources. 7 of 7 configured evaluation feeds currently have results.
- Best LLM for Code CompletionProvisional evidence
36% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from Aider Polyglot or LiveBench Coding. 3 of 3 configured evaluation feeds currently have results.
- Best Local LLM for CodingProvisional evidence
21% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from Aider Polyglot or LiveBench Coding. 4 of 4 configured evaluation feeds currently have results.
- Best LLM for Agentic CodingProvisional evidence
20% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from LiveBench Agentic Coding or LMArena Agent. 7 of 7 configured evaluation feeds currently have results.
- Best LLM for Debugging & Code ReviewProvisional evidence
17% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from Aider Polyglot or LiveBench Coding. 5 of 5 configured evaluation feeds currently have results.
Recommendation coverage
Where this model appears
Not currently included in a published recommendation. The task evidence panel above says exactly what is confirmed and what is still missing.
Catalog data via OpenRouter and models.dev. Last checked within the past 6 hours.