Compare AI models

Specifications
Context windowHow much text the model can hold in mind at once — your question, any documents you attach, the conversation so far, and its own reply. Go past it and the earliest part falls out of view.
1M—
API pricingUSD per 1M tokens · lower wins
Input priceWhat you pay for everything you send the model — your question, plus any documents or earlier conversation you include with it.
$10.00—
Output priceWhat you pay for the text the model writes back. It is normally the dearer half: producing an answer costs more than reading one.
$50.00—
Cached input priceA reduced rate for text you send over and over. If every request starts with the same instructions or the same document, the provider keeps a copy ready and charges less to read it again.
$0.25—
Cheapest inputLowest input rate across every provider on OpenRouter, the lab included. The cheapest endpoint may run a quantised build or a shorter context — see "Available from" on the model page.
$10.00Amazon Bedrock—
Cheapest outputLowest output rate across every provider on OpenRouter, the lab included. May come from a different provider than the cheapest input.
$50.00Amazon Bedrock—
$4,500Anthropic list price—
Benchmarks
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.
89.1%73.7%
Next.js EvalsNext.js coding — Vercel's open eval of how well AI coding agents build and migrate real Next.js apps — measured as the share of tasks the agent completes successfully. Higher is better.
97%58%
Overview
CompanyAnthropicSpaceXSI
Release dateSep 1 2026Mar 19 2026
AccessClosedClosed
Model detailsView modelView model

Frequently asked questions

Claude Fable 5.1 leads Composer 2 on 2 of the 2 benchmarks they both report (SWE-Bench Multilingual, Next.js Evals). Only Claude Fable 5.1 has a verified first-party API price: $10.00 per million input tokens and $50.00 per million output tokens. No pay-as-you-go API rate is tracked for Composer 2. Composer 2 shipped 166 days before Claude Fable 5.1, so benchmark comparisons should account for the intervening progress.

Published specifications for these two models are limited — see each model page for the latest details.

On SWE-Bench Multilingual, Claude Fable 5.1 leads at 89.1% vs Composer 2 at 73.7%. On Next.js Evals, Claude Fable 5.1 leads at 97% vs Composer 2 at 58%.