Anthropic today announced an upgrade to its AI assistant Claude, officially launching the Sonnet 5 model to replace the Sonnet 4.6 released this February. Positioned as the brand's strongest mid-tier option, Sonnet 5 sits between the lightweight Haiku and the flagship Opus in Claude’s product line. According to Anthropic, its performance significantly narrows the gap with Opus 4.8 while maintaining a lower price point.
Per the official release, Sonnet 5 is built to be the "most agentic Sonnet model" yet, capable of autonomously planning, invoking tools like browsers and terminals, and running tasks over extended periods—capabilities previously reserved for larger, more expensive models. Anthropic also announced that Sonnet 5 now serves as the default model for both the free and Pro tiers of Claude, giving all users immediate access. Pricing is set at $2 per million input tokens and $10 per million output tokens, a promotional rate valid until August 31, 2026.