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 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.
81.2%55%
Humanity's Last Exam · with toolsMultidisciplinary reasoning — Humanity's Last Exam — extremely hard expert questions across many subjects. “With tools” means the AI is allowed to search the web or run code while answering. Higher is better.
65.6%50.4%
ARC-AGI-2Abstract reasoning — Puzzle-style tests of abstract reasoning and pattern-finding — the kind of thing people find easy but AIs often struggle with. Higher is better.
90%42.5%
Overview
CompanyAnthropicMeta
Release dateSep 1 2026Apr 8 2026
AccessClosedClosed
Model detailsView modelView model

Frequently asked questions

Claude Fable 5.1 leads Muse Spark on 3 of the 3 benchmarks they both report (SWE-Bench Pro, Humanity's Last Exam, ARC-AGI-2). 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 Muse Spark. Muse Spark shipped 146 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 Pro, Claude Fable 5.1 leads at 81.2% vs Muse Spark at 55%. On Humanity's Last Exam · with tools, Claude Fable 5.1 leads at 65.6% vs Muse Spark at 50.4%. On ARC-AGI-2, Claude Fable 5.1 leads at 90% vs Muse Spark at 42.5%.