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Claude Opus 5 vs GPT-5.3-Codex

GPT-5.3-Codex leads in 2 of 8 categories

Arena ELO

Tie

Cheaper

GPT-5.3-Codex

Faster

Tie

Detailed Comparison

CategoryClaude Opus 5GPT-5.3-Codex
ProviderAnthropic OpenAI
Context Window200K WIN128K
Input Price ($/1M)$15 $1.75 WIN
Output Price ($/1M)$75 $14 WIN
Arena ELON/A N/A
CodingN/A N/A
ReasoningN/A N/A
Speed (tokens/sec)N/A N/A
Open SourceNo No

Frequently Asked Questions

Which is cheaper, Claude Opus 5 or GPT-5.3-Codex?

GPT-5.3-Codex is approximately 83% cheaper than Claude Opus 5 per million tokens.

Which has a larger context window?

Claude Opus 5 supports 200K context, while GPT-5.3-Codex supports 128K.

Is Claude Opus 5 or GPT-5.3-Codex open source?

Claude Opus 5 is proprietary. GPT-5.3-Codex is proprietary.

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