GPT-5.3-Codex vs Grok Code Fast 1
Compare GPT-5.3-Codex by OpenAI against Grok Code Fast 1 by xAI, context windows of 400K vs 256K, tested across 53 shared challenges. Updated April 2026.
Which is better, GPT-5.3-Codex or Grok Code Fast 1?
GPT-5.3-Codex and Grok Code Fast 1 are both competitive models. GPT-5.3-Codex costs $1.75/M input tokens vs $0.2/M for Grok Code Fast 1. Context windows: 400K vs 256K tokens. Compare their real outputs side by side below.
Key Differences Between GPT-5.3-Codex and Grok Code Fast 1
GPT-5.3-Codex is made by openai while Grok Code Fast 1 is from xai. GPT-5.3-Codex has a 400K token context window compared to Grok Code Fast 1's 256K. On pricing, GPT-5.3-Codex costs $1.75/M input tokens vs $0.2/M for Grok Code Fast 1.
No community votes yet. On paper, GPT-5.3-Codex has the edge — bigger model tier, newer, bigger context window.
Grok Code Fast 1 is 9.3x cheaper per token — worth considering if cost matters.
Style Comparison
Grok Code Fast 1 uses 3.9x more transitions
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