Article URL: https://www.tryai.dev/blog/grok-4.5-vs-gpt-5.5-vs-claude-build-off Comments URL: https://news.ycombinator.com/item?id=48838772 Points: 114 # Comments: 56

Grok 4.5 just launched. So we had it, GPT-5.5, Claude Opus 4.8, and Fable 5 one-shot the same interactive apps, then measured latency and cost. Here is who won. Grok 4.5 landed this week with xAI calling it their smartest model yet, "trained alongside Cursor" for coding and agentic work. The internet's favorite way to vibe-check a new coding model is the build-off: hand it one prompt, see what app it spits out, post the clip. So we did it, but properly. We gave Grok 4.5, GPT-5.5, Claude Opus 4.8, and Claude Fable 5 the exact same three prompts: build a single self-contained HTML file (no libraries, no network calls) for an interactive app. One shot each, no hand-holding, no prompt-fiddling. Then we loaded every result in a real browser, poked at it, and recorded what happened. Every clip below is the model's raw output, and you can click "play it live" to run the actual generated app yourself. One rule on failures: if an app did not render at all, we allowed exactly one retry, and we tell you when we used it. Build a colorful, 3D-looking Rubik's Cube with 'Scramble' and 'Solve' buttons. The cube must visibly animate its rotations. This is the mean one. It needs real 3D math, per-face state, and animation, all in one file. The Claudes ran away with this one. Opus 4.8 and Fable 5 both produced a proper, correctly colored 3D cube that scrambles and solves with animated turns, first try. Grok 4.5 stumbled here: its first attempt rendered the title and buttons but no cube at all (a blank void), so we spent our one allowed retry, and the second attempt produced a clean, colorful 3D cube. GPT-5.5 was the odd one out, rendering only a single dark face with barely any color instead of a full cube. Winner: Opus and Fable, tied. An interactive particle gravity sandbox on a canvas: hundreds of particles with trails, clicking adds a heavy attractor. Make it mesmerizing.