GPT OSS Safeguard 20B

GPT OSS Safeguard 20B is part of OpenAI's gpt-oss-safeguard family, introduced as a research preview of open-weight reasoning models built specifically for safety classification work. Rather than baking a fixed policy into the weights, the model interprets a developer-provided safety policy at inference time, using chain-of-thought reasoning to classify user messages, completions, and full conversations against whatever rules the operator supplies, which makes it easier to iterate on policies without retraining.

As the smaller of the two release sizes, GPT OSS Safeguard 20B is a fine-tuned derivative of OpenAI's earlier gpt-oss open models and ships under the same permissive Apache 2.0 license, with weights distributed through Hugging Face. The transparent chain-of-thought lets developers audit how a classification decision was reached, offering a practical middle ground for teams that need customizable, reviewable content moderation without building and labeling their own classifier from scratch.