AI Model Release Tracker

Claude Mythos Preview

Released

Claude Mythos Preview is an AI model released by Anthropic on Tuesday, Apr 7 2026, 49 days after Claude Sonnet 4.6. It has a 1M token context windowHow much information the model can work with in one request, measured in tokens — pieces of words or other data. This includes your question, attachments, conversation and reply. Limits can vary by model variant and provider.. Benchmark results (shown below) cover SWE-Bench Pro, SWE-Bench Verified, SWE-Bench Multilingual, SWE-Bench Multimodal, Terminal-Bench 2.0, CyberGym, and 5 more.

Benchmarks

Coding

SWE-Bench ProAgentic coding — Can the AI fix real bugs in real software? It's handed actual problems from open-source projects and has to write code that genuinely solves them. Higher is better.
77.8%
#7 of 42
SWE-Bench VerifiedCoding — Real coding tasks pulled from open-source projects — the AI has to find and fix actual bugs. A human-checked version of the original SWE-Bench. Higher is better.
93.9%
#4 of 79
SWE-Bench MultilingualMultilingual coding — Like SWE-Bench, but the coding problems span many programming languages, not just one. Tests how broadly the AI can code. Higher is better.
87.3%
#5 of 26
SWE-Bench MultimodalMultimodal coding — Real bug reports that arrive with pictures attached — a screenshot, a mockup, a page rendering wrongly — so the AI has to read the image as well as the code to work out what to fix. Higher is better.
59%
#3 of 12

Terminal & CLI

Terminal-Bench 2.0Agentic terminal coding — Can the AI work in a command-line terminal — running commands and finishing technical setup tasks the way a developer would? (Version 2.0 of the test.) Higher is better.
82%
#2 of 28

Agentic & tool use

CyberGymCybersecurity — Tests the AI on cybersecurity challenges — finding and exploiting software weaknesses inside a safe sandbox. Higher is better.
83.1%
#7 of 17
OSWorld-VerifiedAgentic computer use — Can the AI actually operate a computer — clicking, typing, and using real apps — to finish tasks on its own? Higher is better.
79.6%
#9 of 32

Reasoning & science

Humanity's Last ExamMultidisciplinary reasoning — Humanity's Last Exam — extremely hard expert questions across many subjects, written so you can't just look up the answer. “No tools” means the AI answers on its own. Higher is better.
56.8%no tools
64.7%with tools
no tools
#6 of 48
with tools
#5 of 60
GPQA DiamondScience — Graduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better.
94.5%
#3 of 100

Multimodal

CharXiv ReasoningChart reasoning — Can the AI read and reason about complex charts and figures, not just text? Higher is better.
86.1%
93.2%with tools
#6 of 28
with tools
#3 of 19

Long context

GraphWalks BFS (256K–1M)Long context — breadth-first search F1 on the 200 GraphWalks problems with 256K to 1M tokens of context
80%
#3 of 4

Compare Claude Mythos Preview with

Claude Mythos Preview

Suggested comparisons

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About

Anthropic announced Claude Mythos Preview on April 7, 2026 through Project Glasswing. Selected software maintainers and security teams used it to find and help patch vulnerabilities in widely deployed software. One investigation uncovered a flaw that had been present in OpenBSD for 27 years.

In Anthropic’s CyberGym evaluation, the preview reproduced the target vulnerability on its first attempt in 83.1% of tasks. Opus 4.6 scored 66.6% in the same evaluation. Anthropic committed usage credits to the project and announced rates of $25 per million input tokens and $125 per million output tokens for participants after the preview. In June it offered those partners an upgrade to Claude Mythos 5.

Frequently asked questions

Claude Mythos Preview was released by Anthropic on Tuesday, Apr 7 2026.

All Anthropic releases

33 tracked