GPT-5.3-Codex vs Grok 3 Thinking
Compare GPT-5.3-Codex by OpenAI against Grok 3 Thinking by xAI, context windows of 400K vs 128K, tested across 13 shared challenges. Updated April 2026.
Which is better, GPT-5.3-Codex or Grok 3 Thinking?
GPT-5.3-Codex and Grok 3 Thinking are both competitive models. Context windows: 400K vs 128K tokens. Compare their real outputs side by side below.
Key Differences Between GPT-5.3-Codex and Grok 3 Thinking
GPT-5.3-Codex is made by openai while Grok 3 Thinking is from xai. GPT-5.3-Codex has a 400K token context window compared to Grok 3 Thinking's 128K.
No community votes yet. On paper, GPT-5.3-Codex has the edge — newer, bigger context window.
Style Comparison
GPT-5.3-Codex uses 15.8x more emoji
vsAsk them anything yourself
Some models write identically. You are paying for the brand.
178 models fingerprinted across 32 writing dimensions. Free research.
185x
price gap between models that write identically
178
models
12
clone pairs
32
dimensions
279 AI models invented the same fake scientist.
We read every word. 250 models. 2.14 million words. This is what we found.
