diff --git a/docs/assets/collapse-url-state-demo.gif b/docs/assets/collapse-url-state-demo.gif
new file mode 100644
index 00000000..2411f9e9
Binary files /dev/null and b/docs/assets/collapse-url-state-demo.gif differ
diff --git a/packages/app/src/DBDashboardPage.tsx b/packages/app/src/DBDashboardPage.tsx
index e464de04..6714b08f 100644
--- a/packages/app/src/DBDashboardPage.tsx
+++ b/packages/app/src/DBDashboardPage.tsx
@@ -13,7 +13,7 @@ import { useRouter } from 'next/router';
 import { formatRelative } from 'date-fns';
 import produce from 'immer';
 import { pick } from 'lodash';
-import { parseAsString, useQueryState } from 'nuqs';
+import { parseAsArrayOf, parseAsString, useQueryState } from 'nuqs';
 import { ErrorBoundary } from 'react-error-boundary';
 import RGL, { WidthProvider } from 'react-grid-layout';
 import { useForm, useWatch } from 'react-hook-form';
@@ -1101,38 +1101,42 @@ function DBDashboardPage({ presetConfig }: { presetConfig?: Dashboard }) {
 
   const [editedTile, setEditedTile] = useState<undefined | Tile>();
 
-  const onAddTile = (containerId?: string) => {
-    // Auto-expand collapsed section so the new tile is visible
-    if (containerId && dashboard) {
-      const section = dashboard.containers?.find(s => s.id === containerId);
-      if (section?.collapsed) {
-        setDashboard(
-          produce(dashboard, draft => {
-            const s = draft.containers?.find(c => c.id === containerId);
-            if (s) s.collapsed = false;
-          }),
-        );
-      }
-    }
-    setEditedTile({
-      id: makeId(),
-      x: 0,
-      y: 0,
-      w: 8,
-      h: 10,
-      config: {
-        ...DEFAULT_CHART_CONFIG,
-        source: sources?.[0]?.id ?? '',
-      },
-      ...(containerId ? { containerId } : {}),
-    });
-  };
-
   const sections = useMemo(
     () => dashboard?.containers ?? [],
     [dashboard?.containers],
   );
   const hasSections = sections.length > 0;
+
+  // URL-based collapse state: tracks which sections the current viewer has
+  // explicitly collapsed/expanded. Falls back to the DB-stored default.
+  const [urlCollapsedIds, setUrlCollapsedIds] = useQueryState(
+    'collapsed',
+    parseAsArrayOf(parseAsString).withOptions({ history: 'replace' }),
+  );
+  const [urlExpandedIds, setUrlExpandedIds] = useQueryState(
+    'expanded',
+    parseAsArrayOf(parseAsString).withOptions({ history: 'replace' }),
+  );
+
+  const collapsedIdSet = useMemo(
+    () => new Set(urlCollapsedIds ?? []),
+    [urlCollapsedIds],
+  );
+  const expandedIdSet = useMemo(
+    () => new Set(urlExpandedIds ?? []),
+    [urlExpandedIds],
+  );
+
+  const isSectionCollapsed = useCallback(
+    (section: DashboardContainer): boolean => {
+      // URL state takes precedence over DB default
+      if (collapsedIdSet.has(section.id)) return true;
+      if (expandedIdSet.has(section.id)) return false;
+      return section.collapsed ?? false;
+    },
+    [collapsedIdSet, expandedIdSet],
+  );
+
   const allTiles = useMemo(() => dashboard?.tiles ?? [], [dashboard?.tiles]);
 
   const handleMoveTileToSection = useCallback(
@@ -1287,10 +1291,56 @@ function DBDashboardPage({ presetConfig }: { presetConfig?: Dashboard }) {
     [dashboard, setDashboard],
   );
 
-  // Intentionally persists collapsed state to the server via setDashboard
-  // (same pattern as tile drag/resize). This matches Grafana and Kibana
-  // behavior where collapsed state is saved with the dashboard for all viewers.
+  // Helpers for updating URL-based collapse sets via immer.
+  const addToUrlSet = useCallback(
+    (setter: typeof setUrlCollapsedIds, containerId: string) => {
+      setter(prev =>
+        produce(prev ?? [], draft => {
+          if (!draft.includes(containerId)) draft.push(containerId);
+        }),
+      );
+    },
+    [],
+  );
+
+  const removeFromUrlSet = useCallback(
+    (setter: typeof setUrlCollapsedIds, containerId: string) => {
+      setter(prev => {
+        const next = (prev ?? []).filter(id => id !== containerId);
+        return next.length > 0 ? next : null;
+      });
+    },
+    [],
+  );
+
+  // Toggle collapse in URL state only (per-viewer, shareable via link).
+  // Does NOT persist to DB — the DB `collapsed` field is the default.
   const handleToggleSection = useCallback(
+    (containerId: string) => {
+      const section = dashboard?.containers?.find(s => s.id === containerId);
+      const currentlyCollapsed = section ? isSectionCollapsed(section) : false;
+
+      if (currentlyCollapsed) {
+        addToUrlSet(setUrlExpandedIds, containerId);
+        removeFromUrlSet(setUrlCollapsedIds, containerId);
+      } else {
+        addToUrlSet(setUrlCollapsedIds, containerId);
+        removeFromUrlSet(setUrlExpandedIds, containerId);
+      }
+    },
+    [
+      dashboard?.containers,
+      isSectionCollapsed,
+      addToUrlSet,
+      removeFromUrlSet,
+      setUrlCollapsedIds,
+      setUrlExpandedIds,
+    ],
+  );
+
+  // Toggle the DB-stored default collapsed state (menu action).
+  // This changes what all viewers see by default when opening the dashboard.
+  const handleToggleDefaultCollapsed = useCallback(
     (containerId: string) => {
       if (!dashboard) return;
       setDashboard(
@@ -1303,6 +1353,28 @@ function DBDashboardPage({ presetConfig }: { presetConfig?: Dashboard }) {
     [dashboard, setDashboard],
   );
 
+  const onAddTile = (containerId?: string) => {
+    // Auto-expand collapsed section via URL state so the new tile is visible
+    if (containerId) {
+      const section = dashboard?.containers?.find(s => s.id === containerId);
+      if (section && isSectionCollapsed(section)) {
+        handleToggleSection(containerId);
+      }
+    }
+    setEditedTile({
+      id: makeId(),
+      x: 0,
+      y: 0,
+      w: 8,
+      h: 10,
+      config: {
+        ...DEFAULT_CHART_CONFIG,
+        source: sources?.[0]?.id ?? '',
+      },
+      ...(containerId ? { containerId } : {}),
+    });
+  };
+
   const handleAddSection = useCallback(() => {
     if (!dashboard) return;
     setDashboard(
@@ -1752,26 +1824,32 @@ function DBDashboardPage({ presetConfig }: { presetConfig?: Dashboard }) {
                       <SectionHeader
                         section={section}
                         tileCount={sectionTiles.length}
+                        collapsed={isSectionCollapsed(section)}
+                        defaultCollapsed={section.collapsed ?? false}
                         onToggle={() => handleToggleSection(section.id)}
+                        onToggleDefaultCollapsed={() =>
+                          handleToggleDefaultCollapsed(section.id)
+                        }
                         onRename={newTitle =>
                           handleRenameSection(section.id, newTitle)
                         }
                         onDelete={() => handleDeleteSection(section.id)}
                         onAddTile={() => onAddTile(section.id)}
                       />
-                      {!section.collapsed && sectionTiles.length > 0 && (
-                        <ReactGridLayout
-                          layout={sectionTiles.map(tileToLayoutItem)}
-                          containerPadding={[0, 0]}
-                          onLayoutChange={sectionLayoutChangeHandlers.get(
-                            section.id,
-                          )}
-                          cols={24}
-                          rowHeight={32}
-                        >
-                          {sectionTiles.map(renderTileComponent)}
-                        </ReactGridLayout>
-                      )}
+                      {!isSectionCollapsed(section) &&
+                        sectionTiles.length > 0 && (
+                          <ReactGridLayout
+                            layout={sectionTiles.map(tileToLayoutItem)}
+                            containerPadding={[0, 0]}
+                            onLayoutChange={sectionLayoutChangeHandlers.get(
+                              section.id,
+                            )}
+                            cols={24}
+                            rowHeight={32}
+                          >
+                            {sectionTiles.map(renderTileComponent)}
+                          </ReactGridLayout>
+                        )}
                     </div>
                   );
                 })}
diff --git a/packages/app/src/components/SectionHeader.tsx b/packages/app/src/components/SectionHeader.tsx
index 092acf54..db0e1190 100644
--- a/packages/app/src/components/SectionHeader.tsx
+++ b/packages/app/src/components/SectionHeader.tsx
@@ -13,14 +13,24 @@ import {
 export default function SectionHeader({
   section,
   tileCount,
+  collapsed,
+  defaultCollapsed,
   onToggle,
+  onToggleDefaultCollapsed,
   onRename,
   onDelete,
   onAddTile,
 }: {
   section: DashboardContainer;
   tileCount: number;
+  /** Effective collapsed state (URL state ?? DB default). */
+  collapsed: boolean;
+  /** The DB-stored default collapsed state. */
+  defaultCollapsed: boolean;
+  /** Toggle collapse in URL state (chevron click). */
   onToggle: () => void;
+  /** Toggle the DB-stored default collapsed state (menu action). */
+  onToggleDefaultCollapsed?: () => void;
   onRename?: (newTitle: string) => void;
   onDelete?: () => void;
   onAddTile?: () => void;
@@ -31,7 +41,7 @@ export default function SectionHeader({
   const [menuOpen, setMenuOpen] = useState(false);
 
   const showControls = hovered || menuOpen;
-  const hasMenuControls = onDelete != null;
+  const hasMenuControls = onDelete != null || onToggleDefaultCollapsed != null;
 
   const handleSaveRename = () => {
     const trimmed = editedTitle.trim();
@@ -81,13 +91,13 @@ export default function SectionHeader({
         }
         role="button"
         tabIndex={editing ? undefined : 0}
-        aria-expanded={!section.collapsed}
+        aria-expanded={!collapsed}
         aria-label={`Toggle ${section.title} section`}
       >
         <IconChevronRight
           size={16}
           style={{
-            transform: section.collapsed ? 'rotate(0deg)' : 'rotate(90deg)',
+            transform: collapsed ? 'rotate(0deg)' : 'rotate(90deg)',
             transition: 'transform 150ms ease',
             flexShrink: 0,
             color: 'var(--mantine-color-dimmed)',
@@ -127,7 +137,7 @@ export default function SectionHeader({
             >
               {section.title}
             </Text>
-            {section.collapsed && tileCount > 0 && (
+            {collapsed && tileCount > 0 && (
               <Text size="xs" c="dimmed">
                 ({tileCount} {tileCount === 1 ? 'tile' : 'tiles'})
               </Text>
@@ -170,18 +180,21 @@ export default function SectionHeader({
             </ActionIcon>
           </Menu.Target>
           <Menu.Dropdown>
-            <Menu.Item
-              leftSection={
-                section.collapsed ? (
-                  <IconEye size={14} />
-                ) : (
-                  <IconEyeOff size={14} />
-                )
-              }
-              onClick={onToggle}
-            >
-              {section.collapsed ? 'Expand by Default' : 'Collapse by Default'}
-            </Menu.Item>
+            {onToggleDefaultCollapsed && (
+              <Menu.Item
+                leftSection={
+                  defaultCollapsed ? (
+                    <IconEye size={14} />
+                  ) : (
+                    <IconEyeOff size={14} />
+                  )
+                }
+                onClick={onToggleDefaultCollapsed}
+                data-testid={`section-toggle-default-${section.id}`}
+              >
+                {defaultCollapsed ? 'Expand by Default' : 'Collapse by Default'}
+              </Menu.Item>
+            )}
             {onDelete && (
               <>
                 <Menu.Divider />
diff --git a/packages/app/src/components/__tests__/SectionHeader.test.tsx b/packages/app/src/components/__tests__/SectionHeader.test.tsx
new file mode 100644
index 00000000..54d5a4a9
--- /dev/null
+++ b/packages/app/src/components/__tests__/SectionHeader.test.tsx
@@ -0,0 +1,152 @@
+import React from 'react';
+import { DashboardContainer } from '@hyperdx/common-utils/dist/types';
+import { screen } from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
+
+import SectionHeader from '../SectionHeader';
+
+// Menu buttons have pointer-events:none when not hovered; skip that check.
+const user = userEvent.setup({ pointerEventsCheck: 0 });
+
+const makeSection = (
+  overrides: Partial<DashboardContainer> = {},
+): DashboardContainer => ({
+  id: 'section-1',
+  type: 'section',
+  title: 'My Section',
+  collapsed: false,
+  ...overrides,
+});
+
+describe('SectionHeader', () => {
+  it('renders section title and tile count when collapsed', () => {
+    renderWithMantine(
+      <SectionHeader
+        section={makeSection()}
+        tileCount={3}
+        collapsed={true}
+        defaultCollapsed={false}
+        onToggle={jest.fn()}
+      />,
+    );
+
+    expect(screen.getByText('My Section')).toBeInTheDocument();
+    expect(screen.getByText('(3 tiles)')).toBeInTheDocument();
+  });
+
+  it('does not show tile count when expanded', () => {
+    renderWithMantine(
+      <SectionHeader
+        section={makeSection()}
+        tileCount={3}
+        collapsed={false}
+        defaultCollapsed={false}
+        onToggle={jest.fn()}
+      />,
+    );
+
+    expect(screen.getByText('My Section')).toBeInTheDocument();
+    expect(screen.queryByText('(3 tiles)')).not.toBeInTheDocument();
+  });
+
+  it('calls onToggle (URL state) when chevron area is clicked', async () => {
+    const onToggle = jest.fn();
+    const onToggleDefaultCollapsed = jest.fn();
+
+    renderWithMantine(
+      <SectionHeader
+        section={makeSection()}
+        tileCount={2}
+        collapsed={false}
+        defaultCollapsed={false}
+        onToggle={onToggle}
+        onToggleDefaultCollapsed={onToggleDefaultCollapsed}
+      />,
+    );
+
+    await user.click(
+      screen.getByRole('button', { name: /Toggle My Section section/i }),
+    );
+
+    expect(onToggle).toHaveBeenCalledTimes(1);
+    expect(onToggleDefaultCollapsed).not.toHaveBeenCalled();
+  });
+
+  it('shows "Collapse by Default" when DB default is expanded', async () => {
+    renderWithMantine(
+      <SectionHeader
+        section={makeSection()}
+        tileCount={0}
+        collapsed={false}
+        defaultCollapsed={false}
+        onToggle={jest.fn()}
+        onToggleDefaultCollapsed={jest.fn()}
+        onDelete={jest.fn()}
+      />,
+    );
+
+    // Open the menu
+    await user.click(screen.getByTestId('section-menu-section-1'));
+    expect(await screen.findByText('Collapse by Default')).toBeInTheDocument();
+  });
+
+  it('shows "Expand by Default" when DB default is collapsed', async () => {
+    renderWithMantine(
+      <SectionHeader
+        section={makeSection({ collapsed: true })}
+        tileCount={0}
+        collapsed={true}
+        defaultCollapsed={true}
+        onToggle={jest.fn()}
+        onToggleDefaultCollapsed={jest.fn()}
+        onDelete={jest.fn()}
+      />,
+    );
+
+    await user.click(screen.getByTestId('section-menu-section-1'));
+    expect(await screen.findByText('Expand by Default')).toBeInTheDocument();
+  });
+
+  it('calls onToggleDefaultCollapsed (DB state) from menu item', async () => {
+    const onToggle = jest.fn();
+    const onToggleDefaultCollapsed = jest.fn();
+
+    renderWithMantine(
+      <SectionHeader
+        section={makeSection()}
+        tileCount={0}
+        collapsed={false}
+        defaultCollapsed={false}
+        onToggle={onToggle}
+        onToggleDefaultCollapsed={onToggleDefaultCollapsed}
+        onDelete={jest.fn()}
+      />,
+    );
+
+    await user.click(screen.getByTestId('section-menu-section-1'));
+    await user.click(await screen.findByText('Collapse by Default'));
+
+    expect(onToggleDefaultCollapsed).toHaveBeenCalledTimes(1);
+    expect(onToggle).not.toHaveBeenCalled();
+  });
+
+  it('uses collapsed prop for visual state independent of section.collapsed', () => {
+    // section.collapsed is false (DB default), but collapsed prop is true (URL override)
+    renderWithMantine(
+      <SectionHeader
+        section={makeSection({ collapsed: false })}
+        tileCount={5}
+        collapsed={true}
+        defaultCollapsed={false}
+        onToggle={jest.fn()}
+      />,
+    );
+
+    // Should show tile count because collapsed=true (URL state takes precedence)
+    expect(screen.getByText('(5 tiles)')).toBeInTheDocument();
+    // The aria-expanded should reflect the effective state
+    expect(
+      screen.getByRole('button', { name: /Toggle My Section section/i }),
+    ).toHaveAttribute('aria-expanded', 'false');
+  });
+});