Using Claude Fable 5.1 on OpenRouter

Implementation guide · Claude Fable · Anthropic

Serverless

OpenRouter exposes Claude Fable 5.1 through model ID anthropic/claude-fable-5.1. Use the setup steps, sourced pricing, capabilities, and official provider links below to validate this route before deployment.

Last refreshed 2026-09-01. Next refresh: weekly.

Quick Start

1
Create an account at OpenRouter and generate an API key.
2
Use the OpenRouter SDK or REST API to call anthropic/claude-fable-5.1 — see the documentation for request format.
3
You'll be billed $10.00/1M input, $50.00/1M output tokens. See full pricing.

API Portal Documentation Pricing Model Card

Code Examples

See OpenRouter documentation for integration details.

Pricing on OpenRouter

Type	Price (per 1M)
Input tokens	$10.00
Output tokens	$50.00

Capabilities

VisionMultimodalReasoningJSON / Tool useStructured OutputsPrompt CachingBatch API

About Claude Fable 5.1

Anthropic's generally available Mythos-class model for demanding reasoning, long-horizon agents, and ambitious coding, released September 1, 2026. Same underlying model as Claude Mythos 5.1 with cybersecurity and biology safeguards (flagged queries route to Opus 4.8 for cyber and Opus 5 for biology; those reroutes are not billed at Fable prices). Claude API id claude-fable-5-1. List price $10 per 1M input tokens and $50 per 1M output tokens; cache reads $0.25 per 1M (0.025x base input, 75% less than Fable 5's $1.00).

Full model details →

Model Specs

Released2026-09-01

Context1m

ArchitectureDecoder Only

Knowledge cutoff2026-06

OpenRouter, Inc.

New York, NY, USA