diff --git a/backend/src/driver_db/categories.rs b/backend/src/driver_db/categories.rs
index a8536e8..06cbe01 100644
--- a/backend/src/driver_db/categories.rs
+++ b/backend/src/driver_db/categories.rs
@@ -70,8 +70,60 @@ pub enum Category {
     Oled,
 
     // Timer
+    /// Chips measuring time
     Timer,
 
     #[serde(rename = "Timer::RTC")]
+    /// Clocks that keep track of wall time
+    ///
+    /// Often allow to measure time with an external battery.
     Rtc,
 }
+
+impl Category {
+    /// Get a list of all categories that contain this category
+    pub fn parents(&self) -> Vec<Self> {
+        let mut parents = vec![];
+
+        let mut me = *self;
+        while let Some(parent) = me.parent() {
+            parents.push(parent);
+            me = parent;
+        }
+
+        parents
+    }
+
+    fn parent(&self) -> Option<Self> {
+        Some(match self {
+            Self::Analog => {
+                return None;
+            }
+            Self::Adc => Self::Analog,
+            Self::Dac => Self::Analog,
+            Self::Sensor => {
+                return None;
+            }
+            Self::PowerMeter => Self::Sensor,
+            Self::Accelerometer => Self::Sensor,
+            Self::Gyroscope => Self::Sensor,
+            Self::Magnetometer => Self::Sensor,
+            Self::IoExpander => {
+                return None;
+            }
+            Self::PwmExpander => Self::IoExpander,
+            Self::Actor => {
+                return None;
+            }
+            Self::MotorController => Self::Actor,
+            Self::Display => {
+                return None;
+            }
+            Self::Oled => Self::Display,
+            Self::Timer => {
+                return None;
+            }
+            Self::Rtc => Self::Timer,
+        })
+    }
+}
diff --git a/backend/src/website_db/indexes.rs b/backend/src/website_db/indexes.rs
index 3511616..270f8e9 100644
--- a/backend/src/website_db/indexes.rs
+++ b/backend/src/website_db/indexes.rs
@@ -44,9 +44,12 @@ impl From<&[FullCrate]> for Indexes {
         let mut has_dev_board = BTreeSet::new();
 
         for (i, krate) in value.iter().enumerate() {
-            // TODO also match sub categories
             for cat in &krate.chip_meta.categories {
                 category.add(*cat, i);
+
+                for parent in cat.parents() {
+                    category.add(parent, i);
+                }
             }
 
             for l in krate.licenses() {
diff --git a/driver-db-schema.json b/driver-db-schema.json
index 93f8980..96776a1 100644
--- a/driver-db-schema.json
+++ b/driver-db-schema.json
@@ -48,13 +48,6 @@
     },
     "Category": {
       "oneOf": [
-        {
-          "type": "string",
-          "enum": [
-            "Timer",
-            "Timer::RTC"
-          ]
-        },
         {
           "description": "Devices interacting with analog signals",
           "type": "string",
@@ -124,6 +117,16 @@
           "description": "OLED Screens",
           "type": "string",
           "const": "Display::OLED"
+        },
+        {
+          "description": "Chips measuring time",
+          "type": "string",
+          "const": "Timer"
+        },
+        {
+          "description": "Clocks that keep track of wall time\n\n Often allow to measure time with an external battery.",
+          "type": "string",
+          "const": "Timer::RTC"
         }
       ]
     },
diff --git a/frontend/src/App.svelte b/frontend/src/App.svelte
index 72b1724..50da466 100644
--- a/frontend/src/App.svelte
+++ b/frontend/src/App.svelte
@@ -14,6 +14,7 @@
     const t_crates = crates as FullCrate[];
     let t_indexes = indexes as Indexes;
 
+    let selected_c: number[][] = [];
     let selected_d: number[][] = [];
     let selected_l: number[][] = [];
     let selected_r: number[][] = [];
@@ -42,7 +43,7 @@
         }
     }
 
-    $: selected_crates = combine_filters(t_crates.length, [selected_d, selected_l, selected_r, selected_i, selected_f]);
+    $: selected_crates = combine_filters(t_crates.length, [selected_c, selected_d, selected_l, selected_r, selected_i, selected_f]);
 
 </script>
 
@@ -53,8 +54,9 @@
 <h1>{selected_crates.length} awesome drivers waiting for you!</h1>
 <main>
     <div class="filters">
-        <SortFilter name="Sort by" />
+        <SortFilter name="Sort by"/>
         <TextFilter crates={t_crates} bind:selected={selected_f}/>
+        <Filter name="Categories" values={t_indexes.category} bind:selected={selected_c}/>
         <Filter name="Dependencies" values={t_indexes.dependencies} bind:selected={selected_d}/>
         <Filter name="Interfaces" values={t_indexes.interfaces} bind:selected={selected_i}/>
         <Filter name="👮 License" values={t_indexes.license} bind:selected={selected_l}/>