Claude
What Is Claude Sonnet 3.5 | Performance of the Legacy Model and Differences from Sonnet 4.6
Claude Sonnet 3.5 was retired on October 28, 2025, and new API calls are no longer possible. This article covers the performance, features, and pricing of both versions (20240620 / 20241022) and explains the differences from the current Claude Sonnet 4.6 along with migration steps.