OpenAI Codex Mini vs xAI: Grok 4 Fast (free)
Compare OpenAI Codex Mini by OpenAI against xAI: Grok 4 Fast (free) by xAI, context windows of 200K vs 2.0M, tested across 9 shared challenges. Updated April 2026.
Which is better, OpenAI Codex Mini or xAI: Grok 4 Fast (free)?
OpenAI Codex Mini and xAI: Grok 4 Fast (free) are both competitive models. OpenAI Codex Mini costs $1.5/M input tokens vs $0/M for xAI: Grok 4 Fast (free). Context windows: 200K vs 2000K tokens. Compare their real outputs side by side below.
Key Differences Between OpenAI Codex Mini and xAI: Grok 4 Fast (free)
OpenAI Codex Mini is made by openai while xAI: Grok 4 Fast (free) is from xai. OpenAI Codex Mini has a 200K token context window compared to xAI: Grok 4 Fast (free)'s 2000K. On pricing, OpenAI Codex Mini 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.
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.
