diff --git a/src/App.svelte b/src/App.svelte
index 9c8bb16..2b2216e 100644
--- a/src/App.svelte
+++ b/src/App.svelte
@@ -10,7 +10,7 @@
   import frLocale from '@fullcalendar/core/locales/fr';
   import EventModal from './EventModal.svelte';
   import FilterBar from './FilterBar.svelte';
-  import { mkSource, calendarTree } from './calendar';
+  import { mkSource, calendarTree, initialCalendars, getSubCalendars } from './calendar';
   import { debounce } from 'lodash';
   import Help from './Help.svelte';
 
@@ -30,6 +30,8 @@
     return time.toLocaleTimeString();
   })();
 
+  const params = new URL(document.location).searchParams.getAll('c');
+
   let calendar;
 
   let options = writable({
@@ -71,7 +73,28 @@
     progressiveEventRendering: true
   });
 
+  const flatten = d => {
+    let array = [];
+
+    if (!d) {
+      return [];
+    }
+
+    if (Array.isArray(d)) {
+      d.forEach(a => (array = array.concat(flatten(a))));
+    } else {
+      for (const [n, s] of Object.entries(d)) {
+        array = array.concat(n, flatten(s));
+      }
+    }
+    return array;
+  };
+
   let selectedCalendars = [];
+  const initial =
+    params.length > 0
+      ? flatten(params.map(cal => getSubCalendars(cal))).concat(params)
+      : initialCalendars;
 
   const updateEvents = debounce(calendars => {
     options.update(opts => ({
@@ -88,7 +111,7 @@
 
   <Help />
 
-  <FilterBar {calendarTree} bind:selected={selectedCalendars} />
+  <FilterBar {calendarTree} bind:selected={selectedCalendars} {initial} />
 
   <FullCalendar bind:this={calendar} options={$options} />
 
diff --git a/src/FilterBar.svelte b/src/FilterBar.svelte
index 5b10482..cdcde0b 100644
--- a/src/FilterBar.svelte
+++ b/src/FilterBar.svelte
@@ -5,15 +5,17 @@
 
   export let calendarTree = [];
   export let selected = null;
+  export let initial = [];
 
   let open = false;
+  let icon;
   let generalToggle = writable(true);
   const toggle = () => (open = !open);
 
-  $: icon = () => ($generalToggle ? 'toggle-on' : 'toggle-off');
-
   let subSelections = Array.from({ length: Object.keys(calendarTree).length }, _ => []);
   $: selected = subSelections.flat();
+
+  generalToggle.subscribe(v => (icon = v ? 'toggle-on' : 'toggle-off'));
 </script>
 
 <Button on:click={toggle} class="mb-3 col-6 mx-auto">
@@ -29,7 +31,7 @@
   header="Sélection des calendriers"
 >
   <span class="fs-5 toggle" on:click={() => ($generalToggle = !$generalToggle)}>
-    <Icon name={icon()} />
+    <Icon name={icon} />
     <span class="ms-2">Tous les calendriers</span>
   </span>
   <hr class="my-3" />
@@ -39,7 +41,8 @@
       item={toplevel}
       children={subtrees}
       bind:selected={subSelections[i]}
-      bind:generalToggle
+      generalToggle={$generalToggle}
+      {initial}
     />
   {/each}
 </Offcanvas>
diff --git a/src/FilterItem.svelte b/src/FilterItem.svelte
index de2c632..95432fc 100644
--- a/src/FilterItem.svelte
+++ b/src/FilterItem.svelte
@@ -11,11 +11,15 @@
   export let item = null;
   export let level = 1;
   export let generalToggle = undefined;
+  export let initial;
 
   export let children = [];
   export let selected = [];
-  export let filtering = createTriState(UNCHECKED);
-  let subfiltering = createTriStates(UNCHECKED, Object.entries(children).length);
+
+  const initialState = initial.includes(item) ? CHECKED : UNCHECKED;
+
+  export let filtering = createTriState(initialState);
+  let subfiltering = createTriStates(initialState, Object.entries(children).length);
   let subselected = Array.from({ length: Object.entries(children).length }, _ => []);
 
   let collapsed = Object.entries(children).length ? false : undefined;
@@ -73,11 +77,18 @@
     dispatch('change', { value: evt.detail.value });
   }
 
-  if (generalToggle) {
-    generalToggle.subscribe(value => {
-      setTimeout(() => (value ? filtering.setChecked() : filtering.setUnchecked()), 0);
-      dispatch('change', { value: $filtering });
-    });
+  function handleGeneralToggleChange(value) {
+    if (value) {
+      filtering.setChecked();
+    } else {
+      filtering.setUnchecked();
+    }
+
+    dispatch('change', { value: $filtering });
+  }
+
+  $: if (generalToggle != null) {
+    handleGeneralToggleChange(generalToggle);
   }
 
   const url = (() => {
@@ -85,6 +96,11 @@
     return source ? source.export_url : undefined;
   })();
 
+  setTimeout(
+    () => (initial.includes(item) ? filtering.setChecked() : filtering.setUnchecked()),
+    0
+  );
+
   $: selected =
     $filtering === CHECKED ? [item, ...subselected.flat()] : subselected.flat();
   $: subHidden = () => (collapsed ? 'd-none' : '');
@@ -111,6 +127,7 @@
           filtering={subfiltering.storeAt(i)}
           bind:selected={subselected[i]}
           level={level + 1}
+          {initial}
         />
       {:else}
         <svelte:self
@@ -119,6 +136,7 @@
           filtering={subfiltering.storeAt(i)}
           bind:selected={subselected[i]}
           level={level + 1}
+          {initial}
         />
       {/if}
     {/each}
diff --git a/src/calendar.js b/src/calendar.js
index c53af24..559e10c 100644
--- a/src/calendar.js
+++ b/src/calendar.js
@@ -50,6 +50,12 @@ const calendarsByName = Object.fromEntries(
   Object.entries(calendars).map(([id, { name }]) => [name, id])
 )
 
+export const initialCalendars = Array.from(
+  Object.entries(calendars).map(([_, { name, initial }]) => [name, initial ?? true])
+)
+  .filter(cal => cal[1])
+  .map(cal => cal[0])
+
 export const calendarTree = {
   'Clubs COF': {
     'Club réseau': {},
@@ -68,6 +74,18 @@ export const calendarTree = {
   'K-Fêt': {}
 }
 
+export function getSubCalendars(name, tree = calendarTree) {
+  let ret
+  for (const [cal, subTree] of Object.entries(tree)) {
+    if (cal === name) {
+      ret = subTree
+    } else {
+      ret = ret || getSubCalendars(name, subTree)
+    }
+  }
+  return ret
+}
+
 const calendarIds = Object.keys(calendars)
 
 function mkCalendarUrl(id, { cloud }, extra = {}) {