Anthropic released Claude Fable 5 on June 9, 2026, the first Mythos-class model anyone can use
Pricing doubles Opus 4.8: 10 dollars per million input tokens, 50 out, free on paid plans until June 22
Cyber, bio, and distillation prompts get answered by Opus 4.8 instead, under 5 percent of sessions
SWE-Bench Pro hits 80.3 percent vs 69.2 for Opus 4.8, and Stripe ran a 50-million-line migration in a day
Anthropic put a model above Opus on the shelf. On June 9, 2026 it released Claude Fable 5, the first Mythos-class model available to everyone with an API key, alongside Claude Mythos 5 for a restricted partner circle. I switched my whole studio pipeline to Fable 5 on launch morning. This is what shipped, what it costs, and where the catch is.
What Anthropic Shipped on June 9
Two models, one underlying brain. Claude Fable 5 is the public release. Claude Mythos 5 is the same model with fewer safeguards, reserved for vetted partners. Mythos is not a codename, it is a new model class that sits above Opus in Anthropic's lineup, the way Opus sits above Sonnet. Fable 5 is that class made safe enough to hand to everyone.
The model ID is claude-fable-5. It carries a 1 million token context window and up to 128K output tokens, same envelope as Opus 4.8. Pricing is 10 dollars per million input tokens and 50 per million output. That is exactly double Opus 4.8, which stays at 5 and 25.
Availability moved fast. The API had it on day one. GitHub Copilot flipped it to generally available the same day, Amazon Bedrock listed it, and Claude Code picked it up immediately (this article was produced on it). For subscribers the deal is unusually good: Pro, Max, Team, and seat-based Enterprise plans include Fable 5 at no extra cost from June 9 to June 22. From June 23 it needs usage credits, with a return to standard plans promised once capacity allows. If you pay for Claude, you have a two-week window to test the strongest model Anthropic has ever shipped without spending anything extra.
For developers the migration is one line, with one trap. Fable 5 keeps the Opus 4.8 request surface: adaptive thinking, no sampling parameters, effort levels from low to max. The trap is that an explicit thinking disabled setting now returns a 400 error. Opus 4.8 tolerates it, Fable 5 does not, so omit the field instead and audit any shared request builder before you swap the ID.
Back in May I sorted through the leaks and guesses in and the unusual logic behind it in .
If you want the Claude Code setup I ran this launch-day test on, hooks, commands, and guardrails included, it ships as Claude Blueprint.
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