@innocentzero@social.tchncs.de That's because real ActivityPub differs from what is written in the W3C specification. Traditionally, development of an ActivityPub application required a lot of reverse-engineering because there were no developer documentation (aside from several blog posts), and no good libraries. This is changing, and today there are several well maintained libraries and a guide for ActivityPub developers: https://codeberg.org/ap-next/ap-next/src/branch/main/guide.md (this is what I am working on)