diff --git a/Watchlist-for-ActivityPub-developer-resources.md b/Watchlist-for-ActivityPub-developer-resources.md
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--- a/Watchlist-for-ActivityPub-developer-resources.md
+++ b/Watchlist-for-ActivityPub-developer-resources.md
@@ -130,6 +130,8 @@
 
 #### Utilities
 
+* :black_nib: [**ActivityPubSchema**](https://github.com/redaktor/ActivityPubSchema): JSON Schema definition of the ActivityStreams and ActivityPub specifications. `MIT, Javascript`
+
 * :heavy_check_mark: [**Mastodon Bot Autoresponder**](https://github.com/drequivalent/mastodon-bot-autoresponder) ([Fedi account](https://mastodon.ml/@drq)): a bot that implements group functionality in Mastodon. `MIT, Python`
 
 * :heavy_check_mark: [**OCR Bot**](https://github.com/Lynnesbian/OCRbot/) ([Fedi account](https://fedi.lynnesbian.space/@lynnesbian)): An OCR (Optical Character Recognition) bot for Mastodon (and compatible) instances `AGPL-3.0, Python`