Anthropic · Released Sep 1, 2026Claude Mythos 5.1
Restricted Claude model for advanced cybersecurity and biology research workflows.
- Capability
- —No ECI score yet
- Input
- —No listed price
- Output
- —No listed price
- Context
- 1M128K max output
What it costs
No per-token price is published for this model yet.
No per-token price is listed for this model on models.dev.
Independent benchmarks
Epoch AI has not published a Capabilities Index score for Claude Mythos 5.1 yet.
The details
- Lab
- Anthropic
- Released
- Sep 1, 2026
- Knowledge cutoff
- Jun 2026
- Context window
- 1,000,000 tokens
- Max output
- 128,000 tokens
- Inputs
- Text, Images, PDFs
- Output
- Text
- Reasoning
- Always on
- Tool calling
- Yes
- Structured output
- No
- Weights
- Proprietary
More from Anthropic
About Claude Mythos 5.1
How much does Claude Mythos 5.1 cost?
Claude Mythos 5.1 has no published per-token API price on models.dev yet.
What is the context window of Claude Mythos 5.1?
Claude Mythos 5.1 accepts up to 1,000,000 tokens per request and can write up to 128,000 tokens in one response.
How good is Claude Mythos 5.1?
Epoch AI has not published a Capabilities Index score for Claude Mythos 5.1 yet.
Is Claude Mythos 5.1 open source?
No. Claude Mythos 5.1 is proprietary; you use it through an API or partner platforms.
What inputs does Claude Mythos 5.1 support?
Claude Mythos 5.1 accepts text, images and PDFs and replies in text. It is a reasoning model, supports tool calling.
When was Claude Mythos 5.1 released?
Anthropic released Claude Mythos 5.1 on Sep 1, 2026. Its training data runs to Jun 2026.
What are the best alternatives to Claude Mythos 5.1?
The closest current models from other labs on capability, price and release date are GPT-6 Astra (Fast) (OpenAI, $20.00 / $100.00), Ling 3.0 Flash Sante (inclusionAI, $0.075 / $0.22), Hy4 preview (Tencent, $0.834 / $2.50) and MiniCPM5-2B (OpenBMB).