Simon Willison’s Weblog

Group Membership Protocol. Martin Atkins’ proposal for a simple “is OpenID X a member of group Y?” protocol, useful for whitelists that can scale to handle large numbers of entries.

Posted 22nd January 2007 at 8:27 am

Recent articles

OpenAI are quietly adopting skills, now available in ChatGPT and Codex CLI - 12th December 2025
GPT-5.2 - 11th December 2025
Useful patterns for building HTML tools - 10th December 2025

martin-atkins 7 openid 213 whitelisting 7

Monthly briefing

Sponsor me for $10/month and get a curated email digest of the month's most important LLM developments.

Pay me to send you less!

Sponsor & subscribe