Stay up to date with the latest Claude Sonnet 4 updates, new features, and improvements. Here's what changed in 2026.
Claude Sonnet 4 launched in May 2025 as part of the Claude 4 family alongside Claude Opus 4, introducing hybrid extended thinking, tool use during reasoning, parallel tool calls, and a 65% reduction in reward
hacking shortcuts versus Sonnet
As of April 2026, it remains widely deployed in production via the Anthropic API, Amazon Bedrock, and Google Cloud Vertex AI.
Claude Sonnet 4 is actively developing new features. Check back regularly or follow their official channels for the latest updates.
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Changelog last updated March 2026