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Grok Code Fast 1 vs Claude Opus 4

Compare Grok Code Fast 1 by xAI against Claude Opus 4 by Anthropic, in 5 community votes, claude opus 4 wins 80% of head-to-head duels, context windows of 256K vs 200K, tested across 35 shared challenges. Updated April 2026.

Which is better, Grok Code Fast 1 or Claude Opus 4?

Claude Opus 4 is the better choice overall, winning 80% of 5 blind community votes on Rival. Grok Code Fast 1 costs $0.2/M input tokens vs $15/M for Claude Opus 4. Context windows: 256K vs 200K tokens. Compare their real outputs side by side below.

Key Differences Between Grok Code Fast 1 and Claude Opus 4

Grok Code Fast 1 is made by xai while Claude Opus 4 is from anthropic. Grok Code Fast 1 has a 256K token context window compared to Claude Opus 4's 200K. On pricing, Grok Code Fast 1 costs $0.2/M input tokens vs $15/M for Claude Opus 4. In community voting, In 5 community votes, Claude Opus 4 wins 80% of head-to-head duels.

In 5 community votes, Claude Opus 4 wins 80% of head-to-head duels. Claude Opus 4 leads in Image Generation. Based on blind community voting from the Rival open dataset of 5+ human preference judgments for this pair.

Image Generation: Claude Opus 4 wins 100% of votes
Our Verdict
Claude Opus 4
Claude Opus 4Winner
Grok Code Fast 1
Grok Code Fast 1Runner-up

Pick Claude Opus 4. In 5 blind votes, Claude Opus 4 wins 80% of the time. That's not luck.

Claude Opus 4 particularly excels in Image Generation. Grok Code Fast 1 is 50x cheaper per token — worth considering if cost matters.

Clear winner
Writing DNA

Style Comparison

Similarity
85%

Claude Opus 4 uses 3.6x more lists

Grok Code Fast 1
Claude Opus 4
60%Vocabulary64%
17wSentence Length62w
0.97Hedging0.52
2.8Bold4.4
2.5Lists9.1
0.06Emoji0.11
0.89Headings1.87
0.11Transitions0.27
Based on 23 + 16 text responses
vs

Ask them anything yourself

Grok Code Fast 1Claude Opus 4

Some models write identically. You are paying for the brand.

178 models fingerprinted across 32 writing dimensions. Free research.

Model Similarity Index

185x

price gap between models that write identically

178

models

12

clone pairs

32

dimensions

Devstral M / S
95.7%
Qwen3 Coder / Flash
95.6%
GPT-5.4 / Mini
93.3%
Read the full reportor download the 14-slide PDF

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
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