Claude Sonnet 5: Developer Guide, Benchmarks & Pricing
Anthropic shipped Claude Sonnet 5 (codenamed Fennec) on June 30, 2026 as the new mid-tier workhorse: a 1 million token context window, sharper agentic coding, improved vision, and frontier-class results that close much of the gap to Opus 4.8. This guide covers what shipped, the introductory $2/$10 pricing through August 31, how it stacks up against Sonnet 4.6 and Opus 4.8, and a practical migration checklist.
