GPT-5.3 Codex
GPT-5.3 CodexRankingat xhigh effort?
Alternatives?
CheaperGemini 4 Argonhigh+34%-17%*$1.99Synchronous output stops at 65,536+2BetterGPT-6.1 Sollow+11%-17%$0.13Remove unsupported parameters+5
OpenMiMo v2.6 Prothinking+16%-89%$0.13Pass back reasoning_content+3
CheaperClaude Sonnet 5.5max+29%-17%$5.46No forced tool use+5
CheaperMuse Spark 1.3max+15%-58%$1.60Only auto tool_choice is supported+5Gemini 4 Argonhigh+34%-17%*$1.99Synchronous output stops at 65,536+2Claude Sonnet 5.5max+29%-17%$5.46No forced tool use+5GPT-6.1 Solmax+25%-17%$0.72Remove unsupported parameters+5MiMo v2.6 ProthinkingOpen+16%-89%$0.13Pass back reasoning_content+3Muse Spark 1.3max+15%-58%$1.60Only auto tool_choice is supported+5GPT-6.1 Sollow+11%-17%$0.13Remove unsupported parameters+5MiMo v2.6 ProthinkingOpen+16%-89%$0.13Pass back reasoning_content+3
MiniMax M3.1 Flashthinking+13%-95%$0.22Complete model response must be appendedGPT-6 Solxhigh+9%-17%$0.52Claude Opus 5.5low+14%+66%$0.55No forced tool use+5MiMo v2.6 ProthinkingOpen+16%-89%$0.13Pass back reasoning_content+3
Kimi K3maxOpen+10%+25%$2.00Sampling parameters are fixed+3
Step 5 PreviewthinkingOpen+9%-70%$1.03web_search not available · Chat Completions+2Muse Spark OpenxhighOpen+3%-58%$0.84Reasoning off leaves output unchanged · Self-hosted / llama.cpp+1
DeepSeek V4.1 Flash 1017maxOpensame-89%$0.26Pass back reasoning_content · Chat Completions+4GPT-6 Astraxhigh+28%—$2.31Monitoring can return HTTP 403+2GPT-6.1 Solxhigh+24%—$0.39Remove unsupported parameters+5GPT-5.6 Solxhigh+11%—$1.18GPT-6 Solxhigh+9%—$0.52GPT-5.5xhigh+8%—$2.63Prompts with >272K input tokensGPT-5.4xhigh+3%—$2.50 / $15GPT-5.6 Terraxhighsame—$0.63Prompts with >272K input tokensGPT-5.2xhigh-11%—$1.75 / $14All OpenAI models →History
4 versionsBenchmarks
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Deprecated›
The official model page marks this model deprecated; plan a migration. Source ↗
FAQ
How much does GPT-5.3 Codex cost?›
$1.75 per 1M input tokens and $14 per 1M output tokens; cached input $0.17 per 1M.
Is GPT-5.3 Codex free to use?›
There is no free API; the cheapest paid price is $1.75 per 1M input tokens.
How good is GPT-5.3 Codex, and what is it best at?›
#34 of 334 in Chat & Knowledge, #9 of 239 in Coding, #60 of 242 in Agents & Tool Use, #25 of 245 in Writing & Language, #31 of 124 in Vision & Documents. Strongest at: Tool calling, Reasoning, Science, Long context, Knowledge, Instructions, Vision.
Is GPT-5.3 Codex better than Grok 4.5?›
On Humanity's Last Exam, GPT-5.3 Codex scores 42.5 vs 42.7 — about the same.
How can I use GPT-5.3 Codex?›
Through the API of Azure, OpenAI.
What is the context window of GPT-5.3 Codex?›
400K tokens, with up to 128K output tokens.
When was GPT-5.3 Codex released? Is there a newer version?›
Released 2026-02-05. It has been superseded by GPT-6 Sol.
Is GPT-5.3 Codex open source?›
No, GPT-5.3 Codex is a closed model available through an API. The closest open-weights option here is MiMo v2.6 Pro.
Can GPT-5.3 Codex read images?›
It accepts text and images, PDF files as input.
What is GPT-5.3 Codex?›
GPT-5.3 Codex is a closed language model from OpenAI, released Feb 2026.
What are the best alternatives to GPT-5.3 Codex?›
Gemini 4 Argon (cheaper), GPT-6.1 Sol (better), MiMo v2.6 Pro (open weights).