Claude Sonnet 4.5 vs GPT-5 Codex

Compare Claude Sonnet 4.5 by Anthropic against GPT-5 Codex by OpenAI, in 245 community votes, claude sonnet 4.5 wins 70% of head-to-head duels, tested across 42 shared challenges. Updated April 2026.

Which is better, Claude Sonnet 4.5 or GPT-5 Codex?

Claude Sonnet 4.5 is the better choice overall, winning 70% of 245 blind community votes on Rival. Compare their real outputs side by side below.

Key Differences Between Claude Sonnet 4.5 and GPT-5 Codex

Claude Sonnet 4.5 is made by anthropic while GPT-5 Codex is from openai. In community voting, In 245 community votes, Claude Sonnet 4.5 wins 70% of head-to-head duels.

In 245 community votes, Claude Sonnet 4.5 wins 70% of head-to-head duels. Claude Sonnet 4.5 leads in Web Design, Reasoning, Image Generation. Based on blind community voting from the Rival open dataset of 245+ human preference judgments for this pair.

Web Design: Claude Sonnet 4.5 wins 75% of votes
Reasoning: Claude Sonnet 4.5 wins 59% of votes
Image Generation: Claude Sonnet 4.5 wins 62% of votes
Conversation: Claude Sonnet 4.5 wins 100% of votes
Analysis: Claude Sonnet 4.5 wins 69% of votes
Our Verdict
Claude Sonnet 4.5
Claude Sonnet 4.5Winner
GPT-5 Codex
GPT-5 CodexRunner-up

Pick Claude Sonnet 4.5. In 245 blind votes, Claude Sonnet 4.5 wins 70% of the time. That's not luck.

Claude Sonnet 4.5 particularly excels in Conversation, Web Design, Analysis.

Clear winner
Writing DNA

Style Comparison

Similarity
93%

Claude Sonnet 4.5 uses 5.4x more sentence length

Claude Sonnet 4.5
GPT-5 Codex
64%Vocabulary64%
94wSentence Length17w
0.48Hedging0.38
4.9Bold2.3
8.0Lists3.5
0.45Emoji0.15
1.91Headings0.49
0.07Transitions0.05
Based on 20 + 13 text responses
vs

Ask them anything yourself

Claude Sonnet 4.5GPT-5 Codex

279 AI models invented the same fake scientist.

We read every word. 250 models. 2.14 million words. This is what we found.

AI Hallucination Index 2026
Free preview13 of 58 slides
FAQ

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