GPT-5.3-CodexvsComposer 1.5
GPT-5.3-Codex | Composer 1.5 | |
|---|---|---|
| Benchmarks | ||
Nonsense detection BullshitBench v2Given a confidently-worded but nonsensical prompt, does the AI spot that it makes no sense and push back — instead of playing along and inventing an answer? The score is how often it clearly called out the nonsense. Higher is better. | 24% | — |
Next.js coding Next.js EvalsVercel's open eval of how well AI coding agents build and migrate real Next.js apps — measured as the share of tasks the agent completes successfully. Higher is better. | 83%Best | 67% |
Community preference (code) Arena Elo (Code)Like the text arena, but people vote on which AI writes better code. The votes become a chess-style Elo rating on arena.ai. Higher is better. | 1406 | — |
| Overview | ||
| Company | OpenAI | SpaceXAI |
| Release date | Feb 5 2026 | Feb 9 2026 |
| Access | Proprietary | Proprietary |
Which is better: GPT-5.3-Codex or Composer 1.5?
GPT-5.3-Codex leads Composer 1.5 on 1 of the 1 benchmark they both report (Next.js Evals). GPT-5.3-Codex shipped 4 days before Composer 1.5, so benchmark comparisons should account for the intervening progress.
Published specifications for these two models are limited — see each model page for the latest details.
On Next.js Evals, GPT-5.3-Codex leads at 83% vs Composer 1.5 at 67%.
Frequently asked questions
GPT-5.3-Codex was released by OpenAI on Feb 5 2026.
Composer 1.5 was released by SpaceXAI on Feb 9 2026.
GPT-5.3-Codex leads on Next.js Evals — GPT-5.3-Codex 83% vs Composer 1.5 67%.
Other comparisons
GPT-5.3-CodexvsClaude Opus 5Composer 1.5vsClaude Opus 5GPT-5.3-CodexvsGemini 3.7 FlashComposer 1.5vsGemini 3.7 FlashGPT-5.3-CodexvsMuse GlimmerComposer 1.5vsMuse GlimmerGPT-5.3-CodexvsDeepSeek-V4-Pro-0813Composer 1.5vsDeepSeek-V4-Pro-0813GPT-5.3-CodexvsMistral Medium 3.5Composer 1.5vsMistral Medium 3.5GPT-5.3-CodexvsKimi K3Composer 1.5vsKimi K3