Sonnet 5.5 appears to launch as devs race to live-test it

Anthropic's Sonnet 5.5 appears to have quietly gone live, with Every and multiple developers including Kieran Klaassen launching simultaneous live streams to test the new model.

2026-09-29 ~ 2026-09-29 · 2 related posts

• Sonnet 5.5 appears to be live as builders start testing on stream — every · 2026-09-29
• Builders stream live tests of Sonnet 5.5 as the model appears to go live — kieranklaassen · 2026-09-29