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gpt-oss · 20B

An open-weight reasoning and tool-use model with a publisher-documented Ollama path for consumer hardware.

Verified sourceSource checked 9/23/2026
LOCALRENTED GPUOPEN WEIGHTS

At a glance

Parameters
21B total · 3.6B active
Architecture
Mixture of experts
License
Apache 2.0
Disk space
14 GB
Software
Ollama, vLLM, Transformers
View the model source

Sources and files

Publisher model card and Ollama commands Ollama package size
MY HARDWARE

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Best for

  • Run local reasoning with adjustable effort.
  • Build a private structured-data extraction or tool-use process.

Tradeoffs

  • Use a runtime that handles the model’s Harmony format; direct raw prompting can behave incorrectly.
  • The 14 GB package size does not include all runtime and context memory.

Ways to run it

Ollama · Windows, macOS, Linux

The publisher documents this command; Ollama lists a 14 GB package. It uses the model’s Harmony format.

ollama run gpt-oss:20b
Official instructions

vLLM · Linux

vllm serve openai/gpt-oss-20b
Official instructions

Explore its uses

REASONINGAGENTSTOOLSSTRUCTURED OUTPUT

Get it running

Extract structured data with a local model

Use gpt-oss 20B through Ollama to turn a short text sample into validated JSON fields, then check the output against the source.

View workflow

Keep exploring