BelugAPI
BelugAPI Language

OpenAI GPT OSS 120B

120B-parameter open-weight GPT-OSS style model for general chat and reasoning.

Chat Context window
Text Modalities
General Specialty
Yes Streaming
Get API key — free View docs →
Model ID gpt-oss-120b /v1/chat/completions
Our pricing
Input tokens per 1M tok
$0.350
Output tokens per 1M tok
$0.750
Pay-as-you-go · No minimums · Cancel anytime
OpenAI-compatible ( api.belugapi.com/v1)
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Capabilities

What OpenAI GPT OSS 120B
can do for you.

Native API parity with the official provider — every feature surfaced one-to-one.

Streaming
Server-sent events out of the box

Integration

2-line migration.
Zero friction.

BelugAPI is 100 % compatible with the OpenAI SDK. Point base_url to our endpoint and you're done — no refactoring, no learning curve.

Same request & response schema
Python · Node.js · REST · Go · Ruby
Streaming, tool-calling, structured output
Automatic failover & load balancing
Python 
from openai import OpenAI

client = OpenAI(
  api_key=bel-your-key,
  base_url=https://api.belugapi.com/v1
)

response = client.chat.completions.create(
  model=gpt-oss-120b,
  messages=[{"role": user, "content": Hello!}]
)
print(response.choices[0].message.content)

Highlights

Built for production.

Chat
Long-context capable
High throughput

Complete guide

Everything about
OpenAI GPT OSS 120B.

Specifications, pricing, capabilities, and integration tips — kept up to date with every BelugAPI release.

By BelugAPI 2 min read Updated May 2026

OpenAI's first open-weight reasoning model with 120B parameters (5.1B active MoE). Apache 2.0 license. Runs on single H100 GPU with MXFP4 quantization. Configurable reasoning effort, full chain-of-thought, agentic capabilities with function calling and web browsing.

Overview

OpenAI GPT OSS 120B is a cutting-edge open source llm developed by OpenAI, designed to push the boundaries of artificial intelligence-powered content generation. Released as an open-source model, it empowers developers, researchers, and enterprises to build custom solutions without licensing restrictions.

This model excels in open source, reasoning, agentic, making it a top choice for professionals seeking high-quality, scalable AI solutions. Whether you're building production applications, researching new AI capabilities, or creating stunning visual content, OpenAI GPT OSS 120B delivers industry-leading performance and reliability.

Key Specifications

SpecificationDetails
Model NameOpenAI GPT OSS 120B
ProviderOpenAI
CategoryOpen Source LLM
Model TypeOpen Source Llm
Parameters120B (5.1B active)
LicenseApache 2.0

Key Features & Capabilities

  • Open Source: Advanced capability for professional-grade output.
  • Reasoning: Advanced capability for professional-grade output.
  • Agentic: Advanced capability for professional-grade output.
  • Function Calling: Advanced capability for professional-grade output.
  • Web Browsing: Advanced capability for professional-grade output.
  • Fine Tunable: Advanced capability for professional-grade output.
  • Configurable Reasoning: Advanced capability for professional-grade output.

Use Cases & Applications

  • AI-powered automation
  • Content generation workflows
  • Enterprise AI solutions
  • Creative professional tools

Frequently asked questions

What is OpenAI GPT OSS 120B best used for?

OpenAI GPT OSS 120B excels at open source, reasoning, agentic, making it ideal for professional and enterprise applications.

Who developed OpenAI GPT OSS 120B?

OpenAI GPT OSS 120B was developed by OpenAI, a leading AI research and development company.

What license does OpenAI GPT OSS 120B use?

OpenAI GPT OSS 120B is available under the Apache 2.0 license.

How do I integrate OpenAI GPT OSS 120B into my application?

You can integrate OpenAI GPT OSS 120B via its official API endpoint using standard HTTP requests with your API key. SDKs are available for Python, JavaScript, and other languages.

Ready to ship? Start using OpenAI GPT OSS 120B in under 30 seconds.
Get free API key

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