---
id: "2025-08-05-gpt-oss"
url: "https://postcutoff.com/e/2025-08-05-gpt-oss/"
as_of: "2026-11-13T13:49:00+01:00"
date: "2025-08-05"
date_precision: day
category: open-source
importance: 3
confidence: high
status: [Confirmed]
sources: 2
editor: human editor
human_review: null
version: "2026-10-04"
---

As of: 2026-11-13 13:49 CET.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code), with a human editor. How we work: https://postcutoff.com/about/
Canonical page: https://postcutoff.com/e/2025-08-05-gpt-oss/

# OpenAI releases gpt-oss, its first open-weight LLMs since GPT-2

OpenAI released gpt-oss-120b and gpt-oss-20b, open-weight reasoning models under Apache 2.0; the larger one approached o4-mini on core reasoning benchmarks and ran on a single 80GB GPU.

## Key facts
- Released 5 August 2025
- gpt-oss-120b and gpt-oss-20b, mixture-of-experts
- Apache 2.0 license
- 120b runs on a single 80GB GPU (near-parity with o4-mini on core reasoning, per OpenAI); 20b on devices with 16GB memory
- Active parameters per token: 5.1B (120b) and 3.6B (20b)
- First OpenAI open-weight language models since GPT-2 (2019)

## What happened

OpenAI returned to releasing open weights, partly in response to the rise of Chinese open models.

## Why it matters

Gave the US a competitive open-weight reasoning model and ended OpenAI's six-year hiatus from open releases.

## Your AI and this story

- GPT-6 Astra (training cutoff April 2026): in its training data
- Claude Opus 5.5 (training cutoff June 2026): in its training data
- Gemini 4 Hydrogen (training cutoff March 2026): in its training data
- Grok 4.7 (training cutoff May 2026): in its training data

## Sources

1. [Introducing gpt-oss (OpenAI)](https://openai.com/index/introducing-gpt-oss/) (openai.com, official)
2. [openai/gpt-oss (code)](https://github.com/openai/gpt-oss) (github.com, code)

## Changes

- 2026-09-29 (filed): Created

## Related

- 2025-01-20: [DeepSeek-R1: open-weights reasoning model rivals o1 and shakes markets](https://postcutoff.com/e/2025-01-20-deepseek-r1/index.md)
- 2019-02-14: [OpenAI announces GPT-2 and withholds the full model over misuse concerns](https://postcutoff.com/e/2019-02-14-gpt-2/index.md)