GPT-5.5 vs Claude vs DeepSeek: 3 months of real benchmarks
GPT-5.5 dropped in April 2026. After 3 months of daily use against Claude Sonnet 4.5 and DeepSeek-V4 on actual development work, here is where each model actually wins.
The results (20 real coding tasks)
- Coding (bug fixes, refactors, new features): GPT-5.5 18/20, Claude 17/20, DeepSeek 14/20
- Complex reasoning (multi-step, 5+ constraints): GPT-5.5 17/20, Claude 15/20, DeepSeek 11/20
- Creative writing: Claude 17/20, GPT-5.5 16/20, DeepSeek 13/20
My stack after 3 months
GPT-5.5 has settled into a clear role: the model for hard problems. Debug a race condition that involves the database, the cache layer, and a WebSocket connection? GPT-5.5. Claude is still better at catching subtle bugs in code review and writing with personality. DeepSeek handles bulk tasks at $0.14/M tokens.
For 70% of daily work, any of them are fine. The $200/month Pro tier is expensive but the API pricing ($15/M input) is competitive.
Also tested: GPT IDE
OpenAI's new browser-based code editor. Prompt to deployed app in 30 seconds. Great for prototypes but no terminal, no local files, no git. Not a Cursor replacement yet.
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