FAMILY • 2 MODELS
Anthropic
Every Anthropic model reviewed in the directory.
Browse all model families →Top picks
Fast reasoning model with built-in text watermarking for compliance
Claude Fable 5.1 is Anthropic's Fable-tier creative and reasoning model with integrated text watermarking. Released September 2026 as an update to Claude Fable 5, it features automatic watermarking of all text outputs plus a public detection API to verify AI-generated content. Watermarks are imperceptible to users but machine-verifiable, meeting EU AI Act transparency requirements. Priced competitively as a fast model suitable for high-volume applications.
Paid
Best for Fast Reasoning
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Anthropic's most advanced reasoning model for complex multi-step tasks
Claude Mythos 5.1 is Anthropic's flagship Mythos-tier model released September 2026, representing the most advanced reasoning capabilities in the Claude lineup. Built for research, complex analysis, and multi-step problem solving, it features extended thinking chains, controlled research output, and advanced content moderation. Offers configurable reasoning depth (low/medium/high/xhigh/max) to balance accuracy and latency. Also includes optional text watermarking for transparency.
Paid
Best for Advanced Research
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All models
| Model | Release date | Pricing | Modalities | Best For | Link |
|---|---|---|---|---|---|
| Claude Fable 5.1 | Sep 4, 2026 | Paid | LLMs | Best for Fast Reasoning | View → |
| Claude Mythos 5.1 | Sep 4, 2026 | Paid | LLMs | Best for Advanced Research | View → |