Introducing gpt-oss

gpt-oss-120b & gpt-oss-20b Model Card

We introduce gpt-oss-120b and gpt-oss-20b, two open-weight reasoning models available under the Apache 2. 0 license and our gpt-oss usage policy.

Welcome GPT OSS, the new open-source model family from OpenAI!

PerfReasoning: How Well Do LLMs Reason on Hardware Performance?

PerfReasoning is a new benchmark that tests large language models (LLMs) on their ability to reason about hardware performance and generate analytical performance‑model code. The benchmark presents workloads, architectures, and mapping specifications, asking models to compare mappings and predict off‑chip traffic and buffer requirements. While the best closed‑source models achieve over 90% accuracy on reasoning‑based Q&A and the top open‑weight model scores 82.4%, constructing full performance models remains difficult, with most models scoring below 15% and significant variability across runs. Task‑specific reinforcement learning can improve a 4B model’s mapping‑reasoning accuracy by 15.7 points, but feedback‑free self‑revision prompting is not reliably effective.

OpenLanguageModel: Readable and Composable Small-Language-Model Pretraining for Education and Research

arXiv:2607. 16669v1 Announce Type: cross Abstract: OpenLanguageModel (OLM) is an open-source PyTorch library for building and pretraining small language models while keeping their machinery visible.

Introducing GPT-5.2-Codex

GPT-5. 2-Codex is OpenAI’s most advanced coding model, offering long-horizon reasoning, large-scale code transformations, and enhanced cybersecurity capabilities.

GPT-2: 1.5B release

As the final model release of GPT-2’s staged release, we’re releasing the largest version (1. 5B parameters) of GPT-2 along with code and model weights to facilitate detection of outputs of GPT-2 models.

Introducing GPT-5.2

GPT-5. 2 is our most advanced frontier model for everyday professional work, with state-of-the-art reasoning, long-context understanding, coding, and vision.

OckBench: Measuring the Efficiency of LLM Reasoning

arXiv:2511. 05722v3 Announce Type: replace-cross Abstract: Large language models (LLMs) such as GPT-5 and Gemini 3 have pushed the frontier of automated reasoning and code generation.

Write Once, Run Everywhere: The Axon DSL for Shape-Safe and Framework-Agnostic LLM Architectures

arXiv:2608. 19889v1 Announce Type: new Abstract: The entire ecosystem of open-source language models effectively relies on a single platform.

gpt-oss-safeguard technical report

gpt-oss-safeguard-120b and gpt-oss-safeguard-20b are two open-weight reasoning models post-trained from the gpt-oss models and trained to reason from a provided policy in order to label content under that policy. In this report, we describe gpt-oss-safeguard’s capabilities and provide our baseline safety evaluations on the gpt-oss-safeguard models, using the underlying gpt-oss models as a baseline.

RTL-BenchLS: A Large-Scale Benchmark for RTL Reasoning and Generation with Large Language Models

arXiv:2606. 08976v1 Announce Type: new Abstract: LLM-based RTL generation and reasoning is a promising direction for hardware design automation.

Introducing GPT-5.4

Introducing GPT-5. 4, OpenAI’s most most capable and efficient frontier model for professional work, with state-of-the-art coding, computer use, tool search, and 1M-token context.