Anthropic launched Claude Fable 5 today, its most capable model ever made available to the public. It leads nearly every benchmark the company tested, covering coding, knowledge work, vision, and scientific research.
The model shares the same underlying architecture as Claude Mythos 5, the restricted version running since April through Project Glasswing, a US government cybersecurity collaboration (the Canadian federal government also got access). The difference is guardrails, as Fable 5 has safety classifiers turned on. Mythos 5 has some restrictions lifted for vetted organizations only.
So what are the real-world results? Stripe said Fable 5 compressed months of engineering into days, completing a migration across a 50-million-line Ruby codebase in a single day that would have taken a full team over two months. IMC said it aced their trading analysis evaluations nearly across the board. The model can also rebuild a web app’s source code from screenshots alone, and beat Pokémon FireRed using nothing but raw game visuals with no maps or helper tools–check it out below:
Three query categories trigger a fallback to Claude Opus 4.8 instead of Fable responding: cybersecurity, biology and chemistry, and distillation attempts. Anthropic says these classifiers are deliberately conservative and will sometimes catch harmless requests, but the fallback triggers in less than 5% of sessions on average.
Fable 5 is available today via the Claude API using the model string claude-fable-5. Pricing is $10 per million input tokens and $50 per million output tokens, less than half the cost of Mythos Preview.
Pro, Max, Team, and Enterprise subscribers get access at no extra charge through June 22, after which usage credits will be required until capacity catches up.
This release arrives as Anthropic prepares for its anticipated IPO, following OpenAI’s recent filing and the high-profile market debut of SpaceX this Friday. These companies appear to be accelerating product rollouts to build momentum and capture investor interest ahead of their respective public offerings.
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