diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5c6b491f..babd5965 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,8 @@ Format loosely follows [Keep a Changelog](https://keepachangelog.com).
 
 ### Added
 
+- Expand or collapse every sidebar folder with one click. Thanks [@n00ki](https://github.com/n00ki) for the suggestion! [#272](https://github.com/bholmesdev/hubble.md/pull/272)
+
 ### Changed
 
 ### Fixed
diff --git a/packages/ui/src/components/Sidebar.tsx b/packages/ui/src/components/Sidebar.tsx
index f7164ec5..56c68052 100644
--- a/packages/ui/src/components/Sidebar.tsx
+++ b/packages/ui/src/components/Sidebar.tsx
@@ -34,6 +34,7 @@ import MingcuteCopy2Line from "~icons/mingcute/copy-2-line";
 import MingcuteDeleteLine from "~icons/mingcute/delete-line";
 import MingcuteEditLine from "~icons/mingcute/edit-line";
 import MingcuteExternalLinkLine from "~icons/mingcute/external-link-line";
+import MingcuteFolderLine from "~icons/mingcute/folder-line";
 import MingcuteFolderOpenLine from "~icons/mingcute/folder-open-line";
 import MingcuteMore2Line from "~icons/mingcute/more-2-line";
 import MingcuteNewFolderLine from "~icons/mingcute/new-folder-line";
@@ -476,7 +477,16 @@ export function Sidebar({
 	const highlightPath = pendingPath ?? currentPath;
 	const uncompactFolderId =
 		deleteOnCancel?.kind === "folder" ? deleteOnCancel.path : null;
-	const { collapseFolder, expandFolder, rows, toggleFolder } = useSidebarTree({
+	const {
+		collapseAllFolders,
+		collapseFolder,
+		expandAllFolders,
+		expandFolder,
+		hasExpandedFolders,
+		hasFolders,
+		rows,
+		toggleFolder,
+	} = useSidebarTree({
 		files,
 		folders,
 		getDisplayPath,
@@ -1271,6 +1281,9 @@ export function Sidebar({
 		</DndContext>
 	);
 	const sortLabel = sortMode === "recent" ? "Recent" : "Name";
+	const folderActionLabel = hasExpandedFolders
+		? "Collapse all folders"
+		: "Expand all folders";
 
 	return (
 		<SidebarFrame onCollapse={onCollapse} storageScope={storageScope}>
@@ -1302,6 +1315,23 @@ export function Sidebar({
 							<MingcuteNewFolderLine className="size-3.5" />
 						</Button>
 					)}
+					{hasFolders && (
+						<Button
+							variant="ghost"
+							size="icon-xs"
+							aria-label={folderActionLabel}
+							title={folderActionLabel}
+							onClick={
+								hasExpandedFolders ? collapseAllFolders : expandAllFolders
+							}
+						>
+							{hasExpandedFolders ? (
+								<MingcuteFolderLine className="size-3.5" />
+							) : (
+								<MingcuteFolderOpenLine className="size-3.5" />
+							)}
+						</Button>
+					)}
 					<Select.Root
 						value={sortMode}
 						onValueChange={(mode) => {
diff --git a/packages/ui/src/components/useSidebarTree.test.ts b/packages/ui/src/components/useSidebarTree.test.ts
index ea368a54..c72247a4 100644
--- a/packages/ui/src/components/useSidebarTree.test.ts
+++ b/packages/ui/src/components/useSidebarTree.test.ts
@@ -249,6 +249,48 @@ describe("useSidebarTree", () => {
 		);
 		expect(folderRow(harness.current.rows, "gamma/delta/").expanded).toBe(true);
 	});
+
+	it("expands and collapses every folder", () => {
+		const harness = renderTree({
+			files: nestedFiles,
+			highlightPath: null,
+			storageScope: "workspace",
+		});
+
+		expect(harness.current.hasFolders).toBe(true);
+		expect(harness.current.hasExpandedFolders).toBe(false);
+
+		act(() => harness.current.expandAllFolders());
+
+		expect(harness.current.hasExpandedFolders).toBe(true);
+		expect(filePaths(harness.current.rows)).toEqual([
+			"/workspace/alpha/beta/one.md",
+			"/workspace/gamma/delta/two.md",
+		]);
+		expect(
+			JSON.parse(
+				localStorage.getItem("hubble-sidebar-expanded-folders:workspace") ??
+					"[]",
+			),
+		).toEqual(["alpha/", "alpha/beta/", "gamma/", "gamma/delta/"]);
+
+		act(() => harness.current.collapseAllFolders());
+
+		expect(harness.current.hasExpandedFolders).toBe(false);
+		expect(filePaths(harness.current.rows)).toEqual([]);
+		expect(
+			localStorage.getItem("hubble-sidebar-expanded-folders:workspace"),
+		).toBe("[]");
+	});
+
+	it("reports when the tree has no folders", () => {
+		const harness = renderTree({
+			files: [{ path: "/workspace/note.md" }],
+		});
+
+		expect(harness.current.hasFolders).toBe(false);
+		expect(harness.current.hasExpandedFolders).toBe(false);
+	});
 });
 
 const nestedFiles: SidebarFile[] = [
diff --git a/packages/ui/src/components/useSidebarTree.ts b/packages/ui/src/components/useSidebarTree.ts
index b639d269..ff2cae00 100644
--- a/packages/ui/src/components/useSidebarTree.ts
+++ b/packages/ui/src/components/useSidebarTree.ts
@@ -106,6 +106,11 @@ export function useSidebarTree({
 		expandedFolders,
 		uncompactFolderId,
 	});
+	const folderIds = getFolderIds(tree);
+	const hasFolders = folderIds.size > 0;
+	const hasExpandedFolders = rows.some(
+		(row) => row.kind === "folder" && row.expanded,
+	);
 
 	useEffect(() => {
 		if (!highlightPath || revealedPathRef.current === highlightPath) return;
@@ -147,10 +152,36 @@ export function useSidebarTree({
 	const collapseFolder = (id: string) => setExpanded(id, false);
 	const toggleFolder = (id: string) =>
 		setExpanded(id, !expandedFolders.has(id));
+	const expandAllFolders = () => {
+		setExpandedState({ key: storageKey, folders: folderIds });
+	};
+	const collapseAllFolders = () => {
+		setExpandedState({ key: storageKey, folders: new Set() });
+	};
 
-	return { collapseFolder, expandFolder, rows, toggleFolder };
+	return {
+		collapseAllFolders,
+		collapseFolder,
+		expandAllFolders,
+		expandFolder,
+		hasExpandedFolders,
+		hasFolders,
+		rows,
+		toggleFolder,
+	};
 }
 
+function getFolderIds(root: FolderNode): Set<string> {
+	const ids = new Set<string>();
+	const visit = (folder: FolderNode) => {
+		for (const child of folder.folders.values()) {
+			ids.add(child.id);
+			visit(child);
+		}
+	};
+	visit(root);
+	return ids;
+}
 function makeFolder(id: string, name: string): FolderNode {
 	return {
 		id,