Anthropic
Claude Sonnet 5.5 Releases
Release log
All changesOfficial changelog
Claude Platform release notes - Claude Platform Docs (covers all Anthropic models)
Get an email when we log a new Claude Sonnet 5.5 release
Questions
When was Claude Sonnet 5.5 released
Sep 28, 2026, per platform.claude.com.
Where is the official Claude Sonnet 5.5 changelog
Claude Platform release notes - Claude Platform Docs, at https://platform.claude.com/docs/en/release-notes/overview.
Source: claude.com, read Nov 9, 2026.