Compare GPT-5 Pro by OpenAI against Grok Code Fast 1 by xAI, context windows of 400K vs 256K, tested across 42 shared challenges. Updated April 2026.
GPT-5 Pro and Grok Code Fast 1 are both competitive models. GPT-5 Pro costs $15/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.
GPT-5 Pro is made by openai while Grok Code Fast 1 is from xai. GPT-5 Pro has a 400K token context window compared to Grok Code Fast 1's 256K. On pricing, GPT-5 Pro costs $15/M input tokens vs $0.2/M for Grok Code Fast 1.
No community votes yet. On paper, GPT-5 Pro has the edge — bigger model tier, newer, bigger context window.
Grok Code Fast 1 is 80x cheaper per token — worth considering if cost matters.
Grok Code Fast 1 uses 280.1x more bold
Ask 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.

Compare GPT-5 Pro by OpenAI against Grok Code Fast 1 by xAI, context windows of 400K vs 256K, tested across 42 shared challenges. Updated April 2026.
GPT-5 Pro and Grok Code Fast 1 are both competitive models. GPT-5 Pro costs $15/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.
GPT-5 Pro is made by openai while Grok Code Fast 1 is from xai. GPT-5 Pro has a 400K token context window compared to Grok Code Fast 1's 256K. On pricing, GPT-5 Pro costs $15/M input tokens vs $0.2/M for Grok Code Fast 1.
No community votes yet. On paper, GPT-5 Pro has the edge — bigger model tier, newer, bigger context window.
Grok Code Fast 1 is 80x cheaper per token — worth considering if cost matters.
Grok Code Fast 1 uses 280.1x more bold
Ask 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.

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25+ more head-to-head results. Free. Not a trick.
Free account. No card required. By continuing, you agree to Rival's Terms and Privacy Policy