Anthropic Just Dropped Claude Fable 5 and Claude Mythos 5 — The Most Powerful Models They’ve Ever Released

Anthropic has officially launched two new flagship models: Claude Fable 5 (now available to everyone) and Claude Mythos 5 (restricted access for trusted partners). Both are built on the same “Mythos-class” foundation — the company’s most advanced architecture to date — but they differ in one critical way: safety guardrails.

Fable 5 is the version the public gets. Mythos 5 is essentially the same raw model with some safeguards deliberately relaxed for high-stakes, defensive use cases.

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Fable 5: The New Everyday Powerhouse

Anthropic calls Fable 5 its strongest generally available model ever. It significantly outperforms previous Claude versions across the board:

• Long-horizon coding & agentic tasks — the area where it shines brightest. Models that used to lose the plot after a few steps can now stay on track for hours or even days.
• Analytics & finance reasoning — massive leaps in handling complex spreadsheets, financial models, graphs, and multi-document analysis.
• Vision — dramatically better at extracting precise data from scientific charts, reconstructing web app source code from screenshots, and even near-perfect gameplay of Pokémon FireRed using only in-game images.
• Science, research, and autonomous workflows — longer context, better planning, and fewer mid-task breakdowns.

Real-world proof is already pouring in. Stripe reportedly completed a 50-million-line Ruby codebase migration in a single day — a project that previously would have taken a full engineering team two months.

Cursor, GitHub, Replit, Hebbia, IMC, and Numbers Station are all raving about the jump in long-running, context-heavy tasks.

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Mythos 5: Same Brain, Fewer Brakes

Mythos 5 is the “uncensored” sibling — the full Mythos-class capability with safeguards lifted in specific domains (primarily defensive cybersecurity and certain biomedical research). It’s not a general-purpose “hacker model.” Access is invitation-only for vetted infrastructure partners, cyber defense teams, and (soon) select biomedical researchers.

On any truly dangerous or high-risk query, both models still trigger a safety classifier and fall back to a weaker model (Opus 4.8) for a safe refusal.

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Pricing & Availability (The “Try It Before It Hurts” Window)

• Fable 5 is live right now for all users.
• Pricing: $10 per million input tokens | $50 per million output tokens. Not the cheapest, but the improved success rate on long tasks often makes the economics better than cheaper models that require multiple retries.
• Pro / Max / Team / Enterprise plans: Fable 5 is included **at no extra cost until June 22, 2026**. After that it moves to usage-based credits while Anthropic scales capacity.

Translation: Anthropic knows demand is going to be insane — they’re giving everyone a short, generous window to kick the tires before the meter starts running.

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Why This Matters

Anthropic is clearly preparing for an IPO and wants to show the world it can deliver frontier-level performance while still being responsible. Fable 5 brings Mythos-class power to the masses without crossing the red lines the company has drawn around cyber and bio risks.

If you build SaaS products, internal tools, analytics platforms, or anything that involves long-running reasoning, complex codebases, or heavy document + vision workflows — this is the moment to jump in and experiment while the access is broad and (temporarily) free.

The era of “good enough” long-context agents is over. Claude Fable 5 feels like the first model that can actually act as a reliable thought partner for ambitious, multi-day projects.

Official announcement: Claude Fable 5 and Claude Mythos 5

Go try it before June 22. The window is short, and the upside is huge.