OpenAI gpt-oss-120b
OpenAI gpt-oss-120b
Version: 1
Fireworks•Last updated April 2026
gpt-oss-120b is an open-weight Mixture-of-Experts model from OpenAI with 117B total parameters, designed for powerful reasoning, agentic tasks, and production-grade general-purpose use cases.
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Key capabilities

About this model

Welcome to the gpt-oss series, OpenAI's open-weight models designed for powerful reasoning, agentic tasks, and versatile developer use cases. gpt-oss-120b is used for production, general purpose, high reasoning use-cases that fits into a single H100 GPU.

Key model capabilities

  • Complex reasoning and structured problem-solving (especially with chain-of-thought)
  • Agentic workflows (tool use, web browsing, function calling)
  • Production-grade general-purpose tasks (e.g., coding, math, science)
  • Adjustable reasoning levels

Use cases

See Responsible AI for additional considerations for responsible use.

Key use cases

  • Complex reasoning and structured problem-solving
  • Agentic workflows with tool use and function calling
  • Production-grade coding, math, and science tasks

Out of scope use cases

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Pricing

Pricing is based on a number of factors, including deployment type and tokens used. See pricing details here.

Technical specs

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Training cut-off date

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Training time

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Input formats

Text

Output formats

Text

Supported languages

English

Sample JSON response

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Model architecture

gpt-oss-120b is an open-weight large language model developed by OpenAI with a Mixture-of-Experts (MoE) architecture.
PropertyValue
Total Parameters117B
Activated Parameters5.1B
ArchitectureMixture-of-Experts (MoE)

Long context

Maximum context length: 128K tokens.

Optimizing model performance

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Additional assets

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Training disclosure

Training, testing and validation

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Distribution

Distribution channels

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More information

Model Specifications
Context Length131072
LicenseOther
Last UpdatedApril 2026
Input TypeText
Output TypeText
ProviderFireworks
Languages1 Language