GPT OSS 120B API
About
Build advanced reasoning agents with GPT OSS 120B, a specialized AI model optimized for complex logic and chain-of-thought tasks. This model delivers cost-effective pricing at $0.15/1M input and $0.60/1M output tokens, native tool calling support, open weights architecture. Access GPT OSS 120B via the Fireworks AI API with up to 33K output tokens.
Capabilities
Input Modalities
text
Output Modalities
text
Reasoning
Yes
Structured Output
No
Tool Use
Yes
WeightsOpen
Limits
Context Window
131K
Tokens
Input Limit
131K
Tokens
Max Output
33K
Tokens
Pricing
Standard (per 1M tokens)
Input
$0.15
Output
$0.60
Caching (per 1M tokens)
Read
$0.01
Frequently Asked Questions
GPT OSS 120B by Fireworks AI costs $0.15 per 1M input tokens and $0.60 per 1M output tokens. Cached reads cost $0.01 per 1M tokens.
Model Details
ID
accounts/fireworks/models/gpt-oss-120b
Provider
Fireworks AIFamily
gpt-oss
Release Date
Aug 5, 2025
Knowledge Cutoff
N/A
API Integration
NPM Package
@ai-sdk/openai-compatible
Environment Variables
FIREWORKS_API_KEY
API Base URL
https://api.fireworks.ai/inference/v1/