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Live drop
Mythos 5.1
AnthropicDropped Sep 1, 2026
Same core capabilities as Fable 5.1 with full cyber and bio safeguards for trusted users.
About this release
Live drop
AnthropicDropped Sep 1, 2026
Same core capabilities as Fable 5.1 with full cyber and bio safeguards for trusted users.
About this release
Claude Mythos 5.1 shares the underlying model and capabilities of Fable 5.1 but retains the fuller set of safeguards for cybersecurity and life-sciences work. It is available only through Anthropic’s trusted access programs (Project Glasswing) rather than general availability.
Read the official Anthropic launch pageFirst builds incoming — this lane fills in automatically as people start building with Mythos 5.1. Know one? Submit the URL.