Compare AI models

Specifications
ParametersA rough measure of how big the model is. More parameters usually means more capable and more expensive to run, though it is a poor guide on its own — a smaller, newer model often beats a larger, older one.
—816B
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.
1M1M
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.
$5.00—
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.
$25.00—
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.
$0.50—
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.
$5.00Amazon Bedrock—
Cheapest outputLowest output rate across every provider on OpenRouter, the lab included. May come from a different provider than the cheapest input.
$25.00Amazon Bedrock—
$2,250Anthropic list price—
Benchmarks
Terminal-Bench 2.1Agentic terminal coding — Can the AI work in a command-line terminal — running commands and finishing technical setup tasks the way a developer would? Higher is better.
74.6%76.4%
GDPval-AA v2Knowledge work — economically valuable knowledge work (v2, re-based Elo)
16001401
Overview
CompanyAnthropicMeta
Release dateMay 28 2026Oct 15 2026
AccessClosedOpen Weight
Model detailsView modelView model

Frequently asked questions

Claude Opus 4.8 and Muse Spark Open are evenly matched across the 2 benchmarks they both report (Terminal-Bench 2.1, GDPval-AA v2). Only Claude Opus 4.8 has a verified first-party API price: $5.00 per million input tokens and $25.00 per million output tokens. No pay-as-you-go API rate is tracked for Muse Spark Open. Claude Opus 4.8 shipped 140 days before Muse Spark Open, so benchmark comparisons should account for the intervening progress.

Context windows are 1M (Claude Opus 4.8) vs 1M (Muse Spark Open). Claude Opus 4.8 is closed, while Muse Spark Open is open weight.

On Terminal-Bench 2.1, Muse Spark Open leads at 76.4% vs Claude Opus 4.8 at 74.6%. On GDPval-AA v2, Claude Opus 4.8 leads at 1600 vs Muse Spark Open at 1401.