OpenAI Comes Back to Open Weights, Six Years Later

For nearly six years after GPT-2, OpenAI released no further open-weight models -- every subsequent GPT release, from GPT-3 onward, was closed and API-only. That changed in August 2025 with GPT-OSS-20b, OpenAI's first open-weight release since that shift, published under the fully permissive Apache 2.0 license.

Why it mattered

The release itself was as significant as the model's specific capabilities: one of the industry's most prominent closed-model labs, under competitive pressure from an increasingly capable open-weight ecosystem -- including several other releases in this series -- chose to re-enter open-weight releases directly. It marked a notable shift in how even the most closed labs were positioning themselves relative to the open-weight ecosystem this registry exists to document.

On the record

• Issuer: OpenAI
• License: Apache-2.0
• Claimed cutoff: 2025-08-05
• Status: on-chain, attested

See the full hash breakdown and on-chain attestation on GPT-OSS-20b's Explorer page.