diff --git a/.changeset/tricky-suns-occur.md b/.changeset/tricky-suns-occur.md
new file mode 100644
index 00000000..5e13aa41
--- /dev/null
+++ b/.changeset/tricky-suns-occur.md
@@ -0,0 +1,5 @@
+---
+"runed": minor
+---
+
+feat: `useSupported`
diff --git a/packages/runed/src/lib/functions/index.ts b/packages/runed/src/lib/functions/index.ts
index b9550f29..79a35ccb 100644
--- a/packages/runed/src/lib/functions/index.ts
+++ b/packages/runed/src/lib/functions/index.ts
@@ -4,3 +4,4 @@ export * from "./useDebounce/index.js";
 export * from "./useElementSize/index.js";
 export * from "./useEventListener/index.js";
 export * from "./useMounted/index.js";
+export * from "./useSupported/index.js";
diff --git a/packages/runed/src/lib/functions/useActiveElement/useActiveElement.svelte.ts b/packages/runed/src/lib/functions/useActiveElement/useActiveElement.svelte.ts
index 703cf39d..600b86d6 100644
--- a/packages/runed/src/lib/functions/useActiveElement/useActiveElement.svelte.ts
+++ b/packages/runed/src/lib/functions/useActiveElement/useActiveElement.svelte.ts
@@ -1,14 +1,15 @@
+import { type ReadableBox, box } from "../box/box.svelte.js";
 import { isBrowser } from "$lib/internal/utils/browser.js";
 
 /**
  * Returns a reactive value that is equal to `document.activeElement`.
  * It automatically listens for changes, keeping the reference up to date.
  *
- * @returns an object with a reactive value `value` that is equal to `document.activeElement`, or `null`
- * if there's no active element.
+ * @returns an object with a reactive value `value` that is equal to `document.activeElement`,
+ * or `null` if there's no active element.
  */
-export function useActiveElement(): { value: Readonly<Element | null> } {
-	const activeElement = $state({ value: isBrowser() ? document.activeElement : null });
+export function useActiveElement(): ReadableBox<Element | null> {
+	const activeElement = box(isBrowser() ? document.activeElement : null);
 
 	function onFocusChange() {
 		activeElement.value = document.activeElement;
@@ -24,5 +25,5 @@ export function useActiveElement(): { value: Readonly<Element | null> } {
 		};
 	});
 
-	return activeElement;
+	return box.readonly(activeElement);
 }
diff --git a/packages/runed/src/lib/functions/useElementSize/useElementSize.svelte.ts b/packages/runed/src/lib/functions/useElementSize/useElementSize.svelte.ts
index 30d97567..16c293ce 100644
--- a/packages/runed/src/lib/functions/useElementSize/useElementSize.svelte.ts
+++ b/packages/runed/src/lib/functions/useElementSize/useElementSize.svelte.ts
@@ -1,7 +1,7 @@
 import { box } from "../box/box.svelte.js";
 import type { MaybeBoxOrGetter } from "$lib/internal/types.js";
 
-type Options = {
+export type UseElementSizeOptions = {
 	initialSize?: {
 		width: number;
 		height: number;
@@ -20,7 +20,7 @@ type Options = {
  */
 export function useElementSize(
 	_node: MaybeBoxOrGetter<HTMLElement | undefined>,
-	options: Options = {
+	options: UseElementSizeOptions = {
 		box: "border-box",
 	}
 ): { width: number; height: number } {
diff --git a/packages/runed/src/lib/functions/useMounted/useMounted.svelte.ts b/packages/runed/src/lib/functions/useMounted/useMounted.svelte.ts
index 6d7d7f54..f090ee16 100644
--- a/packages/runed/src/lib/functions/useMounted/useMounted.svelte.ts
+++ b/packages/runed/src/lib/functions/useMounted/useMounted.svelte.ts
@@ -10,6 +10,10 @@ export function useMounted(): ReadableBox<boolean> {
 
 	$effect(() => {
 		untrack(() => (isMounted.value = true));
+
+		return () => {
+			isMounted.value = false;
+		};
 	});
 
 	return box.readonly(isMounted);
diff --git a/packages/runed/src/lib/functions/useSupported/index.ts b/packages/runed/src/lib/functions/useSupported/index.ts
new file mode 100644
index 00000000..c3421e3f
--- /dev/null
+++ b/packages/runed/src/lib/functions/useSupported/index.ts
@@ -0,0 +1 @@
+export * from "./useSupported.svelte.js";
diff --git a/packages/runed/src/lib/functions/useSupported/useSupported.svelte.ts b/packages/runed/src/lib/functions/useSupported/useSupported.svelte.ts
new file mode 100644
index 00000000..019688e2
--- /dev/null
+++ b/packages/runed/src/lib/functions/useSupported/useSupported.svelte.ts
@@ -0,0 +1,25 @@
+import { type ReadableBox, box } from "../box/box.svelte.js";
+
+/**
+ * A hook that takes a predicate determine if a browser API is supported.
+ *
+ * Useful for checking if a browser API is supported before attempting to use it.
+ *
+ * @example
+ * ```ts
+ * const isSupported = useSupported(() => navigator);
+ *
+ * if (isSupported) {
+ * 	// do something with navigator
+ * }
+ * ```
+ */
+export function useSupported(predicate: () => unknown): ReadableBox<boolean> {
+	const isSupported = box(false);
+
+	$effect(() => {
+		isSupported.value = Boolean(predicate());
+	});
+
+	return box.readonly(isSupported);
+}
diff --git a/sites/docs/content/functions/use-supported.md b/sites/docs/content/functions/use-supported.md
new file mode 100644
index 00000000..a12c2eba
--- /dev/null
+++ b/sites/docs/content/functions/use-supported.md
@@ -0,0 +1,18 @@
+---
+title: useSupported
+description: Determine if a feature is supported by the environment before using it.
+---
+
+## Usage
+
+```svelte
+<script lang="ts">
+	import { useSupported } from "runed";
+
+	const isSupported = useSupported(() => navigator && "geolocation" in navigator);
+
+	if (isSupported.value) {
+		// Do something with the geolocation API
+	}
+</script>
+```
diff --git a/sites/docs/mdsx.config.js b/sites/docs/mdsx.config.js
index 49c45cac..742e2679 100644
--- a/sites/docs/mdsx.config.js
+++ b/sites/docs/mdsx.config.js
@@ -64,7 +64,7 @@ const prettyCodeOptions = {
 
 export const mdsxConfig = defineConfig({
 	extensions: [".md"],
-	remarkPlugins: [remarkGfm, remarkRemovePrettierIgnore],
+	remarkPlugins: [remarkGfm, remarkRemovePrettierIgnore, remarkTabsToSpaces],
 	rehypePlugins: [[rehypePrettyCode, prettyCodeOptions], rehypeHandleMetadata, rehypeSlug],
 	blueprints: {
 		default: {
@@ -100,6 +100,22 @@ function remarkRemovePrettierIgnore() {
 	};
 }
 
+/**
+ * Converts tabs to spaces in code blocks to fit more into the viewport.
+ *
+ * @returns {MdastTransformer} - A unified transformer
+ *
+ */
+function remarkTabsToSpaces() {
+	return async (tree) => {
+		visit(tree, "code", (node) => {
+			node.value = node.value
+				// @ts-expect-error - not dealing with this rn
+				.replaceAll("\t", "  ");
+		});
+	};
+}
+
 /**
  * Adds `data-metadata` to `<figure>` elements that contain a `<figcaption>`.
  * We use this to style elements within the `<figure>` differently if a `<figcaption>`
diff --git a/sites/docs/src/lib/config/navigation.ts b/sites/docs/src/lib/config/navigation.ts
index 73f3fc4e..4a94194b 100644
--- a/sites/docs/src/lib/config/navigation.ts
+++ b/sites/docs/src/lib/config/navigation.ts
@@ -91,6 +91,11 @@ export const navigation: Navigation = {
 					href: "/docs/functions/use-mounted",
 					items: [],
 				},
+				{
+					title: "useSupported",
+					href: "/docs/functions/use-supported",
+					items: [],
+				},
 			],
 		},
 	],