Anthropic logo

Claude Mythos Preview

AnthropicProprietaryPending Human Review

Claude Mythos Preview is Anthropic’s published frontier research model, documented in an April 2026 system card and deployed to selected Project Glasswing partners. The general-purpose model demonstrated substantial coding and vulnerability-research capabilities, motivating a restricted defensive-security program rather than general release. It is included as a substantive published research checkpoint, distinct from the later Fable/Mythos 5 family. Partner APIs existed, but no general public inference or open weights were offered.

2026-04-07
Unreleased
Undisclosed proprietary architecture
Proprietary

Specifications

Parameters
Unreleased
Architecture
Undisclosed proprietary architecture
License
Proprietary
Type
text
Modalities
text

Benchmark Scores

Advanced Specifications

Model Family
Claude
API Access
Not Available
Chat Interface
Not Available

Capabilities & Limitations

Capabilities
agentic codingvulnerability analysissecurity researchtool-assisted reasoning
Known Limitations
Restricted Project Glasswing deployment; not generally available.Anthropic describes the checkpoint as unreleased for general use and deprecated its partner identity June 9, 2026.Published evaluations do not establish unrestricted production availability.
Notable Use Cases
defensive security researchcritical-software reviewfrontier-model evaluation

Related Models