Grok 4 Review 2026: xAI Flagship Model, grok-code-fast, Benchmarks and API
Grok 4 launched in Q2 2026 as xAI’s flagship reasoning model, positioned against Claude Opus 4.7 and GPT-5.5 at a competitive $3.50 per million tokens for API access — significantly cheaper than Claude Opus 4.7’s input pricing or GPT-5.5’s $5/million input tokens. The 2M+ context window is the headline spec: processing an entire large codebase or a full book in a single prompt without chunking. The grok-code-fast variant adds a specialized tokenizer optimized for programming tasks. xAI built Colossus — a 100,000+ H100/H200 GPU cluster — specifically for Grok 4’s training, which reflects both the ambition and the resources behind this model. Here’s an honest technical assessment of what Grok 4 delivers versus its benchmarks. ...