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.
—21B
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.
—128k
API pricingUSD per 1M tokens · lower wins
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.
—$0.018Darkbloom
Cheapest outputLowest output rate across every provider on OpenRouter, the lab included. May come from a different provider than the cheapest input.
—$0.09Darkbloom
—$8.10Darkbloom · fp8
Benchmarks
SWE-Bench VerifiedCoding — Real coding tasks pulled from open-source projects — the AI has to find and fix actual bugs. A human-checked version of the original SWE-Bench. Higher is better.
77.4%60.7%
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.
50.4%17.3%
GPQA DiamondScience — Graduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better.
89.5%71.5%
Overview
CompanyMetaOpenAI
Release dateApr 8 2026Aug 5 2025
AccessClosedOpen Weight
Model detailsView modelView model

Frequently asked questions

Muse Spark leads gpt-oss-20b on 3 of the 3 benchmarks they both report (SWE-Bench Verified, Humanity's Last Exam, GPQA Diamond). gpt-oss-20b shipped 246 days before Muse Spark, so benchmark comparisons should account for the intervening progress.

Muse Spark is closed, while gpt-oss-20b is open weight.

On SWE-Bench Verified, Muse Spark leads at 77.4% vs gpt-oss-20b at 60.7%. On Humanity's Last Exam · with tools, Muse Spark leads at 50.4% vs gpt-oss-20b at 17.3%. On GPQA Diamond, Muse Spark leads at 89.5% vs gpt-oss-20b at 71.5%.