Claude Opus 4.5 vs Grok 3 Thinking

Compare Claude Opus 4.5 by Anthropic against Grok 3 Thinking by xAI, tested across 14 shared challenges. Updated April 2026.

Which is better, Claude Opus 4.5 or Grok 3 Thinking?

Claude Opus 4.5 and Grok 3 Thinking are both competitive models. Compare their real outputs side by side below.

Key Differences Between Claude Opus 4.5 and Grok 3 Thinking

Claude Opus 4.5 is made by anthropic while Grok 3 Thinking is from xai.

Our Verdict
Claude Opus 4.5
Claude Opus 4.5
Grok 3 Thinking
Grok 3 Thinking

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
97%

Claude Opus 4.5 uses 15.2x more emoji

Claude Opus 4.5
Grok 3 Thinking
64%Vocabulary46%
55wSentence Length19w
0.86Hedging1.11
5.8Bold3.3
4.5Lists2.6
0.15Emoji0.00
1.59Headings0.64
0.05Transitions0.25
Based on 24 + 6 text responses
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Claude Opus 4.5Grok 3 Thinking

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
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