diff --git a/web/index.html.tpl b/web/index.html.tpl
index 561889a..d5ca35f 100644
--- a/web/index.html.tpl
+++ b/web/index.html.tpl
@@ -514,6 +514,9 @@
               </ul>
             <li>Puzzles, tactics, opening repertoire and training tools</li>
               <ul>
+                <li>
+                  <a href="https://www.theoria.gg/">Theoria: visual repertoire builder & trainer</a>
+                </li>
                 <li>
                   <a href="https://www.chessroots.com/">ChessRoots: a visual opening explorer</a>
                 </li>