Z.ai: GLM 5.1 vs Claude Opus 4.1

Compare Z.ai: GLM 5.1 by Z-ai against Claude Opus 4.1 by Anthropic, context windows of 203K vs 200K, tested across 26 shared challenges. Updated April 2026.

Which is better, Z.ai: GLM 5.1 or Claude Opus 4.1?

Z.ai: GLM 5.1 and Claude Opus 4.1 are both competitive models. Z.ai: GLM 5.1 costs $1.4/M input tokens vs $15/M for Claude Opus 4.1. Context windows: 203K vs 200K tokens. Compare their real outputs side by side below.

Key Differences Between Z.ai: GLM 5.1 and Claude Opus 4.1

Z.ai: GLM 5.1 is made by z-ai while Claude Opus 4.1 is from anthropic. Z.ai: GLM 5.1 has a 203K token context window compared to Claude Opus 4.1's 200K. On pricing, Z.ai: GLM 5.1 costs $1.4/M input tokens vs $15/M for Claude Opus 4.1.

Our Verdict
Claude Opus 4.1
Claude Opus 4.1
Z.ai: GLM 5.1
Z.ai: GLM 5.1Runner-up

No community votes yet. On paper, Claude Opus 4.1 has the edge — bigger model tier, major provider backing.

Z.ai: GLM 5.1 is 17x cheaper per token — worth considering if cost matters.

Too close to call
Writing DNA

Style Comparison

Similarity
98%

Claude Opus 4.1 uses 38.4x more emoji

Z.ai: GLM 5.1
Claude Opus 4.1
54%Vocabulary61%
18wSentence Length87w
0.31Hedging0.54
3.6Bold5.1
2.6Lists6.7
0.00Emoji0.38
0.43Headings1.68
0.11Transitions0.13
Based on 27 + 17 text responses
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Z.ai: GLM 5.1Claude Opus 4.1

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