The OpenAI Assistants API was sunset on August 26, 2026 and no longer works. The replacement is the Responses API plus the Conversations API. What broke, what survives, and the migration step by step, with code.
A practical breakdown of Claude and GPT-4o for product teams in 2026, covering coding performance, writing quality, API pricing, and which model fits which use case.
After building production apps with both Claude Opus 4 and GPT-5.5/5.4, here's what actually matters for application development in 2026. Real benchmarks, not marketing.