GPT-5 Codex vs Grok 3 Thinking

Compare GPT-5 Codex by OpenAI against Grok 3 Thinking by xAI, tested across 14 shared challenges. Updated April 2026.

Which is better, GPT-5 Codex or Grok 3 Thinking?

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

Key Differences Between GPT-5 Codex and Grok 3 Thinking

GPT-5 Codex is made by openai while Grok 3 Thinking is from xai.

Our Verdict
GPT-5 Codex
GPT-5 Codex
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
99%

GPT-5 Codex uses 14.6x more emoji

GPT-5 Codex
Grok 3 Thinking
64%Vocabulary46%
17wSentence Length19w
0.38Hedging1.11
2.3Bold3.3
3.5Lists2.6
0.15Emoji0.00
0.49Headings0.64
0.05Transitions0.25
Based on 13 + 6 text responses
vs

Ask them anything yourself

GPT-5 CodexGrok 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
FAQ

Common questions