From the archive
Claude 4 launches as Claude Code becomes generally available
Claude Opus 4 and Sonnet 4 add two reasoning modes, while Claude Code expands beyond its research preview.
Anthropic launched Claude Opus 4 and Sonnet 4 on May 22, 2025. Both offered quick responses and extended thinking, with availability through Anthropic's API, Amazon Bedrock , and Google Cloud Vertex AI .
Thinking and tools
The models added a beta mode for using tools during extended thinking. This allowed a task to alternate between reasoning and actions such as a web search. The announcement also introduced API features for code execution, files, MCP connections, and longer prompt caching.
Claude Code leaves preview
Claude Code became generally available alongside the models. The coding tool added integrations with VS Code and JetBrains, as well as background tasks through GitHub Actions.
Paid Claude plans included both new models, while Sonnet 4 also reached the free plan. The release expanded the options for coding and agent workflows across chat, direct API access, and cloud platforms.