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AI model · Anthropic

Claude Mythos 5.1

Anthropic released Claude Mythos 5.1 on 1 Sep 2026. API list price: $10.00 per million input tokens and $50.00 per million output tokens. It is not on any public plan: access is restricted to vetted programmes.

The record

each fact with its source

Released

1 Sep 2026

Restricted sibling of Fable 5.1 for vetted cyberdefence and life-science organisations The lab’s announcement

API list price, per million tokens

$10.00 in $50.00 out

Listed with the additional models; access is restricted to vetted programmes. Cached input $0.25.

Anthropic’s pricing page, read 23 Oct 2026

On the free plan?

Restricted

Mythos 5.1 is restricted to vetted trusted-access programmes. Source

The Access Gap, checked 3 Oct 2026

Anthropic’s other recent models

data through 30 Oct 2026

  1. 7 Oct 2026 Claude Haiku 5.5 Fast tier refresh, tuned for high-volume and latency-sensitive work
  2. 28 Sep 2026 Claude Sonnet 5.5 Mid-tier model at $2 in and $10 out, on every platform from launch
  3. 22 Sep 2026 Claude Opus 5.5 Available on every platform from launch
  4. 1 Sep 2026 Claude Fable 5.1 Generally available; its sibling Mythos 5.1 stayed partner-only
  5. 24 Jul 2026 Claude Opus 5 Opus-line generational: near-Fable-5 intelligence at half the price
  6. 30 Jun 2026 Claude Sonnet 5 Sonnet-line generational: close to Opus 4.8 at a fraction of the price
  7. 17 Feb 2026 Claude Sonnet 4.6 Balanced tier upgrade; the default for Free and Pro on claude.ai, and on the API, from launch
  8. 29 Sep 2025 Claude Sonnet 4.5 Best agent value tier

Claude Mythos 5.1 in Anthropic’s full release log · its row on the release chart

Release dates and notes come from the site’s release record, data through 30 Oct 2026; each links the lab’s own announcement. Prices are list prices as the lab’s pricing page printed them on the day shown, before any discount. Something wrong? Tell us.