GPT-5 Codex vs Mistral Medium 3

Compare GPT-5 Codex by OpenAI against Mistral Medium 3 by Mistral AI, tested across 26 shared challenges. Updated April 2026.

Which is better, GPT-5 Codex or Mistral Medium 3?

GPT-5 Codex and Mistral Medium 3 are both competitive models. Compare their real outputs side by side below.

Key Differences Between GPT-5 Codex and Mistral Medium 3

GPT-5 Codex is made by openai while Mistral Medium 3 is from mistral.

Our Verdict
GPT-5 Codex
GPT-5 Codex
Mistral Medium 3
Mistral Medium 3Runner-up

No community votes yet. On paper, GPT-5 Codex has the edge — bigger model tier, newer, major provider backing.

Slight edge
Writing DNA

Style Comparison

Similarity
99%

Mistral Medium 3 uses 3.7x more bold

GPT-5 Codex
Mistral Medium 3
64%Vocabulary57%
17wSentence Length17w
0.38Hedging0.73
2.3Bold8.6
3.5Lists6.5
0.15Emoji0.06
0.49Headings1.18
0.05Transitions0.15
Based on 13 + 15 text responses
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Ask them anything yourself

GPT-5 CodexMistral Medium 3

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

Common questions