Observed 25 September 2026

The page removed a deprecation notice for Claude Mythos Preview and added an entry listing claude-opus-5-5 as Active, with deprecation not expected before September 22, 2027.

what changed matterssummary written by a model — check it against the diff below

A restriction or obligation was removed or reworded — 1 line containing binding language went away. Loosenings are rarely announced.

+1 −1 · c36bd21 → be65ad4 · be65ad4129ac · live page

anthropic/model-deprecations.txt25 Sept 2026

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- Model retirement introduces safety- and model welfare-related risks
At some point, Anthropic hopes to make past models publicly available again. In the meantime, Anthropic has committed to long-term preservation of model weights and other measures to help mitigate these impacts. For more details, see Commitments on Model Deprecation and Preservation .
Model status
Claude Mythos Preview ( claude-mythos-preview ) is deprecated. To migrate to Claude Mythos 5 ( claude-mythos-5 ), see the migration guide .
Current and recently retired models are listed in the following table with their status:
API model name Current state Deprecated Tentative retirement date
claude-fable-5-1 Active N/A Not sooner than September 1, 2027
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claude-fable-5 Active N/A Not sooner than June 9, 2027
claude-mythos-5 Active N/A Not sooner than June 9, 2027
claude-mythos-preview Deprecated June 9, 2026 To be announced
claude-opus-5-5 Active N/A Not sooner than September 22, 2027
claude-opus-5 Active N/A Not sooner than July 24, 2027
claude-opus-4-8 Active N/A Not sooner than May 28, 2027
claude-opus-4-7 Active N/A Not sooner than April 16, 2027
75 unchanged lines

Underlined words mark what moved within a rewritten line. Nothing here is interpreted — this is the difference between two captures, and the conclusion is yours.