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.
—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.
$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—
These models have no shared benchmark scores.
Overview
CompanyAnthropicMeta
Release dateNov 24 2025Oct 15 2026
AccessClosedOpen Weight
Model detailsView modelView model

Frequently asked questions

Claude Opus 4.5 and Muse Spark Open don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. Only Claude Opus 4.5 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 4.5 shipped 325 days before Muse Spark Open, so benchmark comparisons should account for the intervening progress.

Claude Opus 4.5 is closed, while Muse Spark Open is open weight.

Direct benchmark comparisons are unavailable — Claude Opus 4.5 and Muse Spark Open don't publish scores on any of the same benchmarks.