Meet Claude Fable 5
Anthropic’s first publicly available Mythos-class model. Fable5 brings state-of-the-art reasoning to software engineering, science, and knowledge work — with safeguards built in.
First public model to clear 90% on core analytical benchmarks
Higher than Claude Opus on core benchmarks
Red-teamed with no universal jailbreak found
Sessions routed to Opus 4.8 safeguards
What Claude Fable 5 can do
A single Mythos-class model, state-of-the-art across the work that matters most.
Software engineering
Plan, write, and refactor production code across large repositories — the strongest coding model Anthropic has shipped publicly.
Knowledge work
Draft, analyze, and reason over dense documents with the depth expert professionals expect.
Scientific research
Accelerate literature review, hypothesis generation, and analysis across demanding scientific domains.
Vision & UI design
Read complex visuals and turn them into polished, working interface designs.
Game coding
Generate playable game logic and mechanics from a single prompt, end to end.
Advanced reasoning
Mythos-class analytical depth for the hardest, most demanding professional tasks.
Safety
Mythos-class power, responsibly released
Fable 5 is the safeguarded model anyone can use. Mythos 5 is the same underlying model with safeguards lifted — reserved for vetted defenders.
Claude Fable 5
Generally available with safeguards. On sensitive topics like cybersecurity or biology, fewer than 5% of sessions are quietly answered by Claude Opus 4.8 instead.
Claude Mythos 5
The same model with safeguards lifted in some areas — available only to a small group of cyberdefenders and infrastructure providers.
Mythos-class, at half the price
Claude Fable 5 costs less than half of the Claude Mythos Preview — pay only for the tokens you use.
Input
per million tokens
Output
per million tokens
Available through the Claude API, the Claude mobile apps, GitHub Copilot, and Harvey.
Frequently asked questions
Everything you need to know about Claude Fable 5.
Build with Claude Fable 5 today
Bring Mythos-class reasoning into your product. Get API access and start shipping with Anthropic’s most capable public model.