Compare AI models

Specifications
Parameters
—21B
Context window
1M128k
API pricing
Input price
$0.10—
Output price
$0.50—
Cached input price
$0.01—
Cheapest input
—$0.018Darkbloom
Cheapest output
—$0.09Darkbloom
Benchmarks
Humanity's Last Exam · no tools
45.9%10.9%
Humanity's Last Exam · with tools
57.4%17.3%
Overview
CompanyAnthropicOpenAI
Release dateOct 7 2026Aug 5 2025
AccessClosedOpen Weight
Model detailsView modelView model

Frequently asked questions

Claude Haiku 5.5 leads gpt-oss-20b on 2 of the 2 benchmarks they both report (Humanity's Last Exam). Only Claude Haiku 5.5 has a verified first-party API price: $0.10 per million input tokens and $0.50 per million output tokens. No pay-as-you-go API rate is tracked for gpt-oss-20b. gpt-oss-20b shipped 428 days before Claude Haiku 5.5, so benchmark comparisons should account for the intervening progress.

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

On Humanity's Last Exam · no tools, Claude Haiku 5.5 leads at 45.9% vs gpt-oss-20b at 10.9%. On Humanity's Last Exam · with tools, Claude Haiku 5.5 leads at 57.4% vs gpt-oss-20b at 17.3%.