OpenAI/GPT-OSS-120B

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Model ID: gpt-oss-120b OpenAI GPT OSS 120B is an LLM built with a Mixture-of-Experts (MoE) architecture and designed for efficient, large-scale reasoning, coding, and agentic tasks. It excels in processing extremely long contexts—up to 128,000 tokens—while maintaining resource efficiency by activating only a small subset of its total parameters per token, making it practical for both research and production environments. Some other noteworthy features of OpenAI GPT OSS 120B include its suitability for local and private deployments, and its strong performance on tool-use and code generation tasks.

Metric	Value
Parameter Count	117 billion
Mixture of Experts	Yes
Active Parameter Count	5.1 billion
Context Length	128,000 tokens
Multilingual	Yes
Quantized*	Yes
Precision*	MXFP4

*Quantization is specific to the inference provider and the model may be offered with different quantization levels by other providers.

Example request

Use the Workbench as a request builder: configure parameters for this model in the UI, then open the API tab to copy the exact cURL or Python call.

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Basic parameters
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curl -X POST https://hub.oxen.ai/api/ai/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $OXEN_API_KEY" \
  -d '{
  "model": "gpt-oss-120b",
  "messages": [
    {
      "role": "user",
      "content": "Hello, what can you do?"
    }
  ]
}'

curl -X POST https://hub.oxen.ai/api/ai/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $OXEN_API_KEY" \
  -d '{
  "model": "gpt-oss-120b",
  "messages": [
    {
      "role": "user",
      "content": "Hello, what can you do?"
    }
  ],
  "temperature": 0.7,
  "max_tokens": 1024,
  "stream": false
}'

curl -X POST https://hub.oxen.ai/api/ai/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $OXEN_API_KEY" \
  -d '{
  "model": "gpt-oss-120b",
  "messages": [
    {
      "role": "user",
      "content": "Hello, what can you do?"
    }
  ],
  "temperature": 0.7,
  "max_tokens": 1024,
  "stream": false,
  "top_p": 1.0,
  "frequency_penalty": 0,
  "presence_penalty": 0
}'

Fetch model details

The models endpoint returns the full model object, including its json_request_schema.

curl -H "Authorization: Bearer $OXEN_API_KEY" https://hub.oxen.ai/api/ai/models/gpt-oss-120b

Request parameters

This model follows the standard OpenAI chat completions request body. See the chat completions reference for the full parameter list.

Inference API

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​Example request

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​Request parameters

Example request

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Request parameters