Claude Opus 4 vs GPT-5 Nano

Compare Claude Opus 4 by Anthropic against GPT-5 Nano by OpenAI, tested across 32 shared challenges. Updated April 2026.

Which is better, Claude Opus 4 or GPT-5 Nano?

Claude Opus 4 and GPT-5 Nano are both competitive models. Compare their real outputs side by side below.

Key Differences Between Claude Opus 4 and GPT-5 Nano

Claude Opus 4 is made by anthropic while GPT-5 Nano is from openai.

Our Verdict
Claude Opus 4
Claude Opus 4
GPT-5 Nano
GPT-5 Nano

No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.

Too close to call
Writing DNA

Style Comparison

Similarity
100%

Claude Opus 4 uses 444.0x more bold

Claude Opus 4
GPT-5 Nano
64%Vocabulary59%
62wSentence Length25w
0.52Hedging0.23
4.4Bold0.0
9.1Lists4.2
0.11Emoji0.00
1.87Headings0.00
0.27Transitions0.01
Based on 16 + 14 text responses
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Ask them anything yourself

Claude Opus 4GPT-5 Nano

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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