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Claude Opus 4.1 vs Mistral Medium 3.5

1 vs 1 benchmarks won

Anthropic
Claude Opus 4.1
Mistral
Mistral Medium 3.5
Overview
CompanyAnthropicMistral
Release dateAug 5 2025Apr 29 2026
Model type
Open sourceNoYes
Specifications
Parameters
128B
Context window
256k
Benchmarks
Science reasoning
GPQA Diamond
80.9%
Software engineering
SWE-Bench Verified
74.5%
77.6%
Multimodal understanding
MMMU
Timeline
Release gapClaude Opus 4.1 shipped 267 days before Mistral Medium 3.5

Which is better: Claude Opus 4.1 or Mistral Medium 3.5?

Claude Opus 4.1 and Mistral Medium 3.5 are evenly matched across the benchmarks they both publish. Claude Opus 4.1 shipped 267 days before Mistral Medium 3.5, so benchmark comparisons should account for the intervening progress.

Mistral Medium 3.5 is an open-source / open-weight model; Claude Opus 4.1 is proprietary.

On SWE-Bench Verified, Mistral Medium 3.5 scores 77.6%, 3.1 points above Claude Opus 4.1 at 74.5%.

Frequently asked questions

When was Claude Opus 4.1 released?
Claude Opus 4.1 was released by Anthropic on Aug 5 2025.
When was Mistral Medium 3.5 released?
Mistral Medium 3.5 was released by Mistral on Apr 29 2026.
Which is better at coding, Claude Opus 4.1 or Mistral Medium 3.5?
On SWE-Bench Verified (real-world software-engineering tasks), Mistral Medium 3.5 leads — Claude Opus 4.1 scores 74.5% and Mistral Medium 3.5 scores 77.6%.
Is Claude Opus 4.1 or Mistral Medium 3.5 open source?
Mistral Medium 3.5 is an open-source / open-weight model released by Mistral. Claude Opus 4.1 is a proprietary model released by Anthropic.

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