Anthropic Unleashes Claude Fable 5 and Mythos 5, Bringing Next-Gen Power to the Public

Anthropic has officially launched its highly anticipated "Mythos-class" artificial intelligence models, Claude Fable 5 and Claude Mythos 5, shattering existing industry benchmarks. This milestone marks the first time Anthropic’s most advanced AI architecture is available to a wider audience.

Both models share the same underlying architecture, capable of executing complex, autonomous tasks over extended periods. In early testing, Stripe reported that Fable 5 compressed months of software engineering work into a single day by autonomously executing a codebase migration across 50 million lines of code.

To safely scale this power, Anthropic developed a unique dual-model release. Claude Fable 5 is built for general public use and features strict safety classifiers. If a user prompt touches on high-risk topics like cybersecurity, biology, or chemistry, the query automatically routing to the slightly less powerful Claude Opus 4.8. Meanwhile, Claude Mythos 5—the unrestricted version—remains exclusive to vetted partners and government infrastructure operators under Project Glasswing, where it serves as the world's strongest cybersecurity model.

Claude Fable 5 is available today via the Claude API, Amazon Bedrock, and paid subscription plans. It remains free for Pro, Max, and Enterprise subscribers until June 22, after which it will transition to a usage-based credit system.

Reference: Anthropic