Compare AI models

Specifications
ParametersThe learned values that shape how a model responds. B means billion and T means trillion. For mixture-of-experts models, the total count is larger than the number active for each token. Parameter count alone does not measure quality.
—21B
Context windowHow much information the model can work with in one request, measured in tokens — pieces of words or other data. This includes your question, attachments, conversation and reply. Limits can vary by model variant and provider.
1M128k
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.
$4.00—
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.
$20.00—
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.
$0.20—
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.
$4.00Amazon Bedrock$0.004PrimeIntellect
Cheapest outputLowest output rate across every provider on OpenRouter, the lab included. May come from a different provider than the cheapest input.
$20.00Amazon Bedrock$0.017PrimeIntellect
$1,800Anthropic list price$1.65PrimeIntellect · fp4
Benchmarks
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.
67.7%17.3%
Overview
CompanyAnthropicOpenAI
Release dateSep 22 2026Aug 5 2025
AccessClosedOpen Weight
Model detailsView modelView model

Frequently asked questions

Claude Opus 5.5 leads gpt-oss-20b on 1 of the 1 benchmark they both report (Humanity's Last Exam). Only Claude Opus 5.5 has a verified first-party price for an available API: $4.00 per million input tokens and $20.00 per million output tokens. No currently available pay-as-you-go API rate is tracked for gpt-oss-20b. gpt-oss-20b shipped 413 days before Claude Opus 5.5, so benchmark comparisons should account for the intervening progress.

Context windows are 1M (Claude Opus 5.5) vs 128k (gpt-oss-20b). Claude Opus 5.5 is closed, while gpt-oss-20b is open weight.

On Humanity's Last Exam · with tools, Claude Opus 5.5 leads at 67.7% vs gpt-oss-20b at 17.3%.