Claude Mythos Preview (Reasoning)

by Anthropic

Claude Mythos Preview (Reasoning) is a reasoning model from Anthropic, released on April 7, 2026. API pricing is $25 per 1M input tokens and $125 per 1M output tokens. It ranks #5 of 220 models by Intelligence Score with a score of 54.4.

Claude Mythos Preview is an unreleased general-purpose frontier model from Anthropic, a new tier above Opus (internal codename 'Capybara'). It identified thousands of zero-day vulnerabilities across every major operating system and web browser as part of Project Glasswing, a cross-industry cybersecurity initiative with 12 partners including AWS, Apple, Microsoft, and Google. State-of-the-art on SWE-bench Verified (93.9%), GPQA Diamond (94.6%), USAMO (97.6%), Terminal-Bench 2.0 (82.0%), CyberGym (83.1%), and Cybench (100% pass@1, saturated). Represents a 4.3x increase over the previous trendline for model performance. Deployed under ASL-3 Standard. Best-aligned Claude model to date per Anthropic's risk report, with the first-ever 24-hour internal alignment review before deployment. Not planned for general availability. Pricing for participants: $25/$125 per million tokens (input/output). 244-page system card.

Key specs

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