Simon Willison’s Weblog

Understanding a Protocol. Andrew’s latest notes on how ActivityPub and Mastodon work under the hood, based on his extensive development work building out Takahē.

Posted 6th December 2022 at 12:50 am

Recent articles

My Lethal Trifecta talk at the Bay Area AI Security Meetup - 9th August 2025
The surprise deprecation of GPT-4o for ChatGPT consumers - 8th August 2025
GPT-5: Key characteristics, pricing and model card - 7th August 2025

andrew-godwin 19 mastodon 34 activitypub 10

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