gpt-oss-20b (free) API
About
Build advanced reasoning agents with gpt-oss-20b (free), a specialized AI model optimized for complex logic and chain-of-thought tasks. This model delivers available completely free of charge, native tool calling support, open weights architecture. Access gpt-oss-20b (free) via the OpenRouter API with up to 33K output tokens.
Capabilities
Input Modalities
text
Output Modalities
text
Reasoning
Yes
Structured Output
Yes
Tool Use
Yes
WeightsOpen
Temperature
Adjustable
Attachment
Not Supported
Limits
Context Window
131K
Tokens
Input Limit
131K
Tokens
Max Output
33K
Tokens
Pricing
Standard (per 1M tokens)
Input
Free
Output
Free
Frequently Asked Questions
gpt-oss-20b (free) by OpenRouter costs Free per 1M input tokens and Free per 1M output tokens.
Model Details
ID
openai/gpt-oss-20b:free
Provider
OpenRouterFamily
gpt-oss
Release Date
Aug 5, 2025
Knowledge Cutoff
Jun 30, 2024
API Integration
NPM Package
@openrouter/ai-sdk-provider
Environment Variables
OPENROUTER_API_KEY
API Base URL
https://openrouter.ai/api/v1