@al1r4d

independent from any language, the checklist is

read the specifications in the correct order :)
This means you can read the protocol spec. first to get an overview https://www.w3.org/TR/activitypub/
but all of these W3C recommendations have "Normative References" and you need to understand them from the bottom up first, roughly the stack is
1) https (you can use other transport mechanisms but this is common)
2) Linked Data

3) JSON-LD (the underlying Linked Data format)
https://www.w3.org/TR/json-ld/
4) The definition of the Vocabulary
https://www.w3.org/TR/activitystreams-core/
5) The Vocabulary
https://www.w3.org/TR/activitystreams-vocabulary
6) The protocol
https://www.w3.org/TR/activitypub/

[and apart from it natural language values for multilanguage and rel links and e.g. webfinger for mastodon]

Then you can go on with nedjos checklist
https://socialhub.activitypub.rocks/t/guide-for-new-activitypub-implementers/479

#activitypub #activitystreams #dev

PS
my language is JS / deno