GPT-3.5 Turbo vs xAI: Grok 4 Fast (free)
Compare GPT-3.5 Turbo by OpenAI against xAI: Grok 4 Fast (free) by xAI, context windows of 16K vs 2.0M, tested across 34 shared challenges. Updated April 2026.
Which is better, GPT-3.5 Turbo or xAI: Grok 4 Fast (free)?
GPT-3.5 Turbo and xAI: Grok 4 Fast (free) are both competitive models. GPT-3.5 Turbo costs $1.5/M input tokens vs $0/M for xAI: Grok 4 Fast (free). Context windows: 16K vs 2000K tokens. Compare their real outputs side by side below.
Key Differences Between GPT-3.5 Turbo and xAI: Grok 4 Fast (free)
GPT-3.5 Turbo is made by openai while xAI: Grok 4 Fast (free) is from xai. GPT-3.5 Turbo has a 16K token context window compared to xAI: Grok 4 Fast (free)'s 2000K. On pricing, GPT-3.5 Turbo costs $1.5/M input tokens vs $0/M for xAI: Grok 4 Fast (free).
No community votes yet. On paper, xAI: Grok 4 Fast (free) has the edge — bigger model tier, newer, bigger context window.
Style Comparison
xAI: Grok 4 Fast (free) uses 138.0x more bold
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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
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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.
