diff --git a/master.html b/master.html
index 28f79805..34c38564 100644
--- a/master.html
+++ b/master.html
@@ -193,6 +193,7 @@ with the WSGI server</a></li>
 Clients</a>
 <ul>
 <li class="level4"><a href="#davx⁵" id="toc-davx⁵">DAVx⁵</a></li>
+<li class="level4"><a href="#onecalendar" id="toc-onecalendar">OneCalendar</a></li>
 <li class="level4"><a href="#gnome-calendar-contacts" id="toc-gnome-calendar-contacts">GNOME Calendar, Contacts</a></li>
 <li class="level4"><a href="#evolution" id="toc-evolution">Evolution</a></li>
 <li class="level4"><a href="#thunderbird" id="toc-thunderbird">Thunderbird</a></li>
@@ -1348,7 +1349,8 @@ instead of returning the results.</p>
 <h2>Supported Clients <a class="headerlink" href="#supported-clients">&para;</a></h2>
 <p>Radicale has been tested with:</p>
 <ul>
-<li><a href="https://android.com/">Android</a> with <a href="https://www.davx5.com/">DAVx⁵</a> (formerly DAVdroid)</li>
+<li><a href="https://android.com/">Android</a> with <a href="https://www.davx5.com/">DAVx⁵</a> (formerly DAVdroid),</li>
+<li><a href="https://www.onecalendar.nl/">OneCalendar</a></li>
 <li><a href="https://wiki.gnome.org/Apps/Calendar">GNOME Calendar</a>,
 <a href="https://wiki.gnome.org/Apps/Contacts">Contacts</a> and <a href="https://wiki.gnome.org/Apps/Evolution">Evolution</a></li>
 <li><a href="https://www.mozilla.org/thunderbird/">Mozilla
@@ -1375,6 +1377,15 @@ Radicale server is <a href="#ssl">accessible over HTTPS</a>.</p>
 <code>http://localhost:5232</code>) and your username. DAVx⁵ will show
 all existing calendars and address books and you can create new.</p>
 </section>
+<section class="level4" id="onecalendar">
+<h4>OneCalendar <a class="headerlink" href="#onecalendar">&para;</a></h4>
+<p>When adding account, select CalDAV account type, then enter user
+name, password and the Radicale server (e.g.
+<code>https://yourdomain:5232</code>). OneCalendar will show all
+existing calendars and (FIXME: address books), you need to select which
+ones you want to see. OneCalendar supports many other server types
+too.</p>
+</section>
 <section class="level4" id="gnome-calendar-contacts">
 <h4>GNOME Calendar, Contacts <a class="headerlink" href="#gnome-calendar-contacts">&para;</a></h4>
 <p>GNOME 46 added CalDAV and CardDAV support to <em>GNOME Online