diff --git a/README.md b/README.md
index 1994ef3..bdac0e7 100644
--- a/README.md
+++ b/README.md
@@ -5,4 +5,5 @@
 - Chapter by freeCodeCamp ([Source](https://github.com/freeCodeCamp/chapter)) *new*, JavaScript
 - [GetTogether](https://gettogether.community/) ([Source](https://github.com/GetTogetherComm/GetTogether)), *mature*, Python
 - [Mobilizon](https://joinmobilizon.org/en/) ([Source](https://framagit.org/framasoft/mobilizon/)), *in development*, Elixir
+- [on_ruby](https://www.onruby.eu/) ([Source](https://github.com/phoet/on_ruby)), *mature*, Ruby
 - Open Event (Source: [Frontend](https://github.com/fossasia/open-event-frontend), [Backend](https://github.com/fossasia/open-event-server)) *mature*, Python