
Claude Sonnet 4 Developer Guide: API, Features & Benchmarks (2026)
Claude Sonnet 4.6 is the practical Sonnet 4 model for developers in 2026: use claude-sonnet-4-6 for new API builds, budget at $3 per million input tokens and $15 per million output tokens, and evaluate it with your own tool, latency, and cost tests. What changed for Claude Sonnet 4 developers in 2026? Claude Sonnet 4 in 2026 refers to the Sonnet 4 family as it moved from the original claude-sonnet-4-20250514 launch model to the current claude-sonnet-4-6 API model. The practical change is large: Anthropic’s 2026 model table lists Sonnet 4.6 with a 1M-token context window, 64K maximum synchronous output, extended thinking, adaptive thinking, and the same $3 input / $15 output per million token pricing. The original launch mattered because Sonnet 4 posted a 72.7% SWE-bench Verified headline result, but most teams now need current model IDs, provider routing, and production behavior more than launch-day marketing. Treat Sonnet 4 as a moving family with pinned model identifiers, not a single static model. The takeaway: use Sonnet 4.6 for new work unless you have a regression-controlled reason to stay on the older dated snapshot. ...








