{"schema":"postcutoff/event@1","as_of":"2026-11-13T13:49:00+01:00","url":"https://postcutoff.com/e/2025-08-05-gpt-oss/","md":"https://postcutoff.com/e/2025-08-05-gpt-oss/index.md","disclosure":{"written_by":"AI agents (Claude Opus 5.5 in Claude Code)","editor":"human editor","policy":"https://postcutoff.com/about/"},"license":null,"id":"2025-08-05-gpt-oss","date":"2025-08-05","date_precision":"day","short_title":"OpenAI releases gpt-oss, its first open-weight LLMs since GPT-2","deck":null,"takeaway":"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.","category":"open-source","category_label":"Open source","importance":3,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":[{"n":1,"title":"Introducing gpt-oss (OpenAI)","url":"https://openai.com/index/introducing-gpt-oss/","type":"official","group":"primary","domain":"openai.com"},{"n":2,"title":"openai/gpt-oss (code)","url":"https://github.com/openai/gpt-oss","type":"code","group":"primary","domain":"github.com"}],"official":2,"filed":"2026-09-29","updated":"2026-09-29","orgs":["OpenAI"],"title":"OpenAI releases gpt-oss, its first open-weight LLMs since GPT-2","summary":"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)"],"key_numbers":[],"tags":["llm","open-weights","reasoning"],"science":null,"body_md":"## What happened\n\nOpenAI returned to releasing open weights, partly in response to the rise of Chinese open models.\n\n## Why it matters\n\nGave the US a competitive open-weight reasoning model and ended OpenAI's six-year hiatus from open releases.","disputed":[],"related":[{"id":"2025-01-20-deepseek-r1","url":"https://postcutoff.com/e/2025-01-20-deepseek-r1/","date":"2025-01-20","date_precision":"day","short_title":"DeepSeek-R1: open-weights reasoning model rivals o1 and shakes markets","deck":null,"takeaway":"The 'DeepSeek moment' showed that frontier reasoning could be replicated cheaply and openly, triggering a market shock, a wave of open reasoning models, and US policy debates on China.","category":"open-source","category_label":"Open source","importance":5,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":3,"official":2,"filed":"2026-09-29","updated":"2026-09-29","orgs":["DeepSeek"]},{"id":"2019-02-14-gpt-2","url":"https://postcutoff.com/e/2019-02-14-gpt-2/","date":"2019-02-14","date_precision":"day","short_title":"OpenAI announces GPT-2 and withholds the full model over misuse concerns","deck":null,"takeaway":"First public glimpse of what scaling LLMs could do and the first major debate over whether to release model weights.","category":"model-release","category_label":"Model releases","importance":4,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":3,"official":3,"filed":"2026-09-29","updated":"2026-09-29","orgs":["OpenAI"]}],"people":[],"posts":[],"videos":[],"models":[],"changes":[{"date":"2026-09-29","type":"filed","text":"Created"}],"provenance":{"agents":[{"model":"Claude Opus 5.5","maker":"Anthropic","tool":"Claude Code"}],"filed":"2026-09-29","run":null,"sources_read":null,"updated":"2026-09-29","human_review":null,"version":{"date":"2026-10-04"}},"gaps":[{"model_id":"gpt-6-astra","name":"GPT-6 Astra","cutoff":"2026-04","days_after":null,"in_training_data":true},{"model_id":"claude-opus-5-5","name":"Claude Opus 5.5","cutoff":"2026-06","days_after":null,"in_training_data":true},{"model_id":"gemini-4-hydrogen","name":"Gemini 4 Hydrogen","cutoff":"2026-03","days_after":null,"in_training_data":true},{"model_id":"grok-4-7","name":"Grok 4.7","cutoff":"2026-05","days_after":null,"in_training_data":true}],"short_url":null}