Responses API — Simon Carter

Two OpenAI shutdowns land on 26 August 2026: o3 leaves ChatGPT and the Assistants API is gone for good

On 26 August 2026, OpenAI removes o3 from ChatGPT's model picker and permanently shuts down the Assistants API. Here's what breaks and what to do.

23 August 2026

Developer Tools & APIs

OpenAI Assistants API is permanently removed on 26 August 2026: here's what you need to do

OpenAI's Assistants API is gone on 26 August 2026. This is a full architectural migration to the Responses API, not a quick endpoint swap.

3 August 2026

Developer Tools & APIs

OpenAI's Secure MCP Tunnel lets private servers talk to ChatGPT without opening your firewall

OpenAI's GA Secure MCP Tunnel uses an outbound-only tunnel-client daemon so private MCP servers can serve ChatGPT, Codex, and the Responses API with no inbound firewall rules.

Updated 29 July 2026