Claude Sonnet 5.5 (free lane) is a balanced model from Anthropic, available here under the exact model id “claude-sonnet-5-5:free”. In the Claude line-up here it sits between Claude Sonnet 5 and Claude Sonnet 5.5. Anthropic has not published a release date we can cite; it has been available here since 11 Nov 2026.
Anthropic documents tools, vision, reasoning and structured output for it, and it reads images as well as text.
It costs $1.40 per million input tokens and $7 per million output tokens, so output is 5× the input rate. On the use cases below, output makes up 38% of the bill for daily coding, 23% for code review and 73% for writing, so trimming the context you send saves more than capping the answer. With a 3:1 input-to-output mix it ranks 21st lowest-cost of the 27 models on this site.
There is no discounted cached-input rate for this model, so every input token bills at $1.40 per million.
It is served through the OpenAI-compatible format at https://api.oneaiapikey.com/v1, so any SDK or tool that lets you set a custom base URL, for example Codex CLI, Cursor and Cline, can use it. It is not offered on the Anthropic Messages endpoint; pick an Anthropic-format model for Claude Code.