openai
POST /v1/chat/completionsGPT-5.3 Codex
gpt-5.3-codexGPT-5.3-Codex is OpenAI’s agentic coding model for Codex and similar development environments. It combines frontier software engineering performance with broader reasoning and professional knowledge, supports configurable reasoning effort, and is listed with a 400K context window and 128K max output tokens. OpenAI positions it as moving Codex beyond writing and reviewing code toward using computers, running terminal workflows, iterating on web apps, and handling real-world engineering tasks over long horizons.
Total Context
400Ktokens
Max Output
128Ktokens
Released
Feb 5, 2026
Modalities
GPT-5.3 Codex Price
| Input Price | Output Price | Cache Read |
|---|---|---|
| $1.75/M | $14/M | $0.175/M |
GPT-5.3 Codex API
GPT-5.3 Codex Benchmark
GPT-5.3 Codex (xhigh)
44.3
/100
Artificial Analysis Intelligence Index
Artificial Analysis broad capability aggregate
Index score
53.1
/100
Artificial Analysis Coding Index
Artificial Analysis software task aggregate
Index score
Knowledge & Reasoning
GPQA
Advanced science problem solving
91.5%
HLE
Broad expert-level exam set
39.9%
Coding & Engineering
SciCode
Scientific coding challenges
53.2%
Terminal-Bench Hard
Hard terminal task execution
53.0%
Instruction Following & Agent Tasks
IFBench
Prompt constraint adherence
75.4%
AA-LCR
Long-context reasoning
74%
τ²-Bench
Agent workflow tasks
86.0%
Metrics sourced from Artificial Analysis
GPT-5.3 Codex FAQ
GPT-5.3 Codex: capabilities, use cases, limits, and TokenHub guidance.
What role does GPT-5.3 Codex play?+
GPT-5.3 Codex is a OpenAI model for long-running agentic coding and repository work.
What should I try first with GPT-5.3 Codex?+
Best for repository-scale development, debugging and refactoring and research and synthesis, especially when software-engineering quality is the priority.
Why choose GPT-5.3 Codex?+
Key strength: agentic coding optimized for long-running research and execution.
What tradeoff comes with GPT-5.3 Codex?+
Its coding specialization is less suitable for broad general conversation or multimodal analysis. For broad general or multimodal work is needed, consider GPT-5.5.
How should I start in TokenHub?+
Use the exact ID shown by TokenHub; follow your account docs and verify current features.
Media and Discussions
Selected public videos and posts related to this model.
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