Claude Fable 5.1 (free lane) is a flagship model from Anthropic, available here under the exact model id “claude-fable-5-1:free”. It heads the Claude line-up here, above Claude Fable 5.1, Claude Opus 5.5 (free lane), Claude Opus 5.5, Claude Sonnet 5, Claude Sonnet 5.5 (free lane), Claude Sonnet 5.5, Claude Haiku 4.5 and Claude Haiku 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 $7 per million input tokens and $35 per million output tokens, so output is 5× the input rate. On the use cases below, output makes up 20% of the bill for long agent runs, 68% for front-end code and 71% for analysis, so capping max tokens and asking for diffs saves more than trimming the prompt. With a 3:1 input-to-output mix it ranks 26th 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 $7 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.