Modelpeers
Claude Sonnet 4.5 character

Claude Sonnet 4.5

Model at Anthropic

Retiring

Takes effect Nov 30, 2026 · in 29 days

Claude Sonnet 4.5 deprecated, retiring November 30, 2026

Anthropic announced that claude-sonnet-4-5-20250929 will retire on the Claude API on November 30, 2026, with Claude Sonnet 5.5 as the recommended replacement.

Who is affected:
Apps calling claude-sonnet-4-5-20250929.
Action needed:
Migrate to claude-sonnet-5-5 before November 30, 2026.

Source

"with retirement on the Claude API scheduled for November 30, 2026."

Claude Platform release notes (API)

Published

Open the sourceplatform.claude.com

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