Anthropic
Cyber
Big
Closed weights
Claude Mythos 5.1
58 days since Anthropic announced it ·
Claude Mythos 5.1 is a closed-weights cyber model from Anthropic, announced 15 Sep 2026.
- Input
- —
- per 1M tokens
- Cache write
- —
- per 1M tokens
- Cache read
- —
- per 1M tokens
- Output
- —
- per 1M tokens
- Context window
- —
- tokens
- Parameters
- —
- not disclosed
No price on the lab’s own pages.
- Announcement
- anthropic.com/claude-fable-and-mythos-5-1
Our coverage
We haven’t written about Claude Mythos 5.1 yet.
Anthropic · Big · Mythos
closed weights- Claude Mythos 5.2 +55d
- Claude Mythos 5.1 +98d
- Claude Mythos 5
More from Anthropic
All modelsFacts last updated , from Anthropic’s own pages.