diff --git a/appinfo/routes.php b/appinfo/routes.php
index 54eef3f..4916137 100644
--- a/appinfo/routes.php
+++ b/appinfo/routes.php
@@ -2,9 +2,13 @@
 
 return [
   'routes' => [
-    ['name' => 'timeGate#timeGate', 'url' => '/timegate/{url}',
+    ['name' => 'timeGate#singleUserTimeGate', 'url' => '/u/{userId}/timegate/{url}',
       'requirements' => array('url' => '.+')],
-    ['name' => 'timeMap#timeMap', 'url' => '/timemap/{url}',
+    ['name' => 'timeGate#allUsersTimeGate', 'url' => '/timegate/{url}',
+      'requirements' => array('url' => '.+')],
+    ['name' => 'timeMap#singleUserTimeMap', 'url' => '/u/{userId}/timemap/{url}',
+      'requirements' => array('url' => '.+')],
+    ['name' => 'timeMap#allUsersTimeMap', 'url' => '/timemap/{url}',
       'requirements' => array('url' => '.+')],
   ]
 ];
diff --git a/lib/Controller/TimeGateController.php b/lib/Controller/TimeGateController.php
index 1657946..41f8e0b 100644
--- a/lib/Controller/TimeGateController.php
+++ b/lib/Controller/TimeGateController.php
@@ -6,37 +6,56 @@ require_once __DIR__ . '/datetimeConversion.php';
 require_once __DIR__ . '/getUrlParameter.php';
 
 use OCP\IRequest;
-use OCP\IURLGenerator;
 use OCP\IServerContainer;
 use OCP\AppFramework\Controller;
 use OCP\AppFramework\Http\RedirectResponse;
 use OCP\AppFramework\Http\DataDisplayResponse;
 
 class TimeGateController extends Controller {
-	private $userFolder;
-	private $URLGenerator;
+	use MementoFinder;
+
+	private $loggedInUserId;
+	private $serverContainer;
 
 	public function __construct(
 		$AppName,
 		IRequest $request,
 		$UserId,
-		IServerContainer $serverContainer,
-		IURLGenerator $URLGenerator
+		IServerContainer $serverContainer
 	) {
 		parent::__construct($AppName, $request);
-		$this->userFolder = $serverContainer->getUserFolder($UserId);
-		$this->URLGenerator = $URLGenerator;
+		$this->loggedInUserId = $UserId;
+		$this->serverContainer = $serverContainer;
 	}
 
 	/**
 	 * @NoAdminRequired
 	 * @NoCSRFRequired
+	 * @PublicPage
 	 */
-	public function timeGate($url) {
-		$url = getUrlParameter('timegate'); // XXX workaround, as nextcloud corrupts the $url parameter.
+	public function singleUserTimeGate($userId, $url) {
+		// XXX workaround, as nextcloud corrupts the $url parameter.
+		$url = getUrlParameter("u/$userId/timegate");
+
+		$matchingMementos = $this->findSingleUserMementosForUrl($userId, $url);
+
+		return $this->makeResponse($url, $matchingMementos);
+	}
 
-		$matchingMementos = findMementos($this->userFolder, $url);
+	/**
+	 * @NoAdminRequired
+	 * @NoCSRFRequired
+	 * @PublicPage
+	 */
+	public function allUsersTimeGate($url) {
+		$url = getUrlParameter('timegate');
+
+		$matchingMementos = $this->findAllUsersMementosForUrl($url);
+
+		return $this->makeResponse($url, $matchingMementos);
+	}
 
+	private function makeResponse($url, $matchingMementos) {
 		// Choose one of the matched mementos, if any.
 		if (count($matchingMementos) === 0) {
 			// No matches. :(
@@ -69,12 +88,17 @@ class TimeGateController extends Controller {
 		// Send a 302 Found redirect pointing to the chosen memento.
 		$response = new RedirectResponse($chosenMemento['mementoUrl']);
 		$response->setStatus(302);
-		$response->addHeader('Vary', 'accept-datetime');
+		// Both the requested datetime and the authenticated user influence the response.
+		$response->addHeader('Vary', 'accept-datetime, cookie');
 
-		// Add a link to the original and to the timemap.
-		$originalLink = "<{$chosenMemento['originalUrl']}>;rel=\"original\"";
+		// Add a link to the original(s) and to the timemap.
+		$originalLinks = implode(", ", array_map(
+			function ($originalUrl) { return "<$originalUrl>;rel=\"original\""; },
+			$chosenMemento['originalUrls']
+		));
 		// XXX hardcoding the route URL.
-		$timeMapUrl = $this->URLGenerator->getAbsoluteUrl("/apps/memento/timemap/$url");
+		$timeMapUrl = $this->serverContainer->getURLGenerator()
+			->getAbsoluteUrl("/apps/memento/timemap/$url");
 		$firstDatetime = datetimeTimestampToString($matchingMementos[0]['datetime']);
 		$lastMemento = $matchingMementos[count($matchingMementos)-1];
 		$lastDatetime = datetimeTimestampToString($lastMemento['datetime']);
@@ -82,14 +106,13 @@ class TimeGateController extends Controller {
 			. ";rel=\"timemap\""
 			. ";type=\"application/link-format\""
 			. ";from=\"$firstDatetime\";until=\"$lastDatetime\"";
-		$response->addHeader('Link', "$originalLink, $timeMapLink");
+		$response->addHeader('Link', "$originalLinks, $timeMapLink");
 
 		return $response;
 	}
 }
 
 function minBy($array, $iteratee) {
-	// is there any simpler way for this in php?
 	$values = array_map($iteratee, $array);
 	$argmin = array_search(min($values), $values);
 	return $array[$argmin];
diff --git a/lib/Controller/TimeMapController.php b/lib/Controller/TimeMapController.php
index 918a139..08bc8fc 100644
--- a/lib/Controller/TimeMapController.php
+++ b/lib/Controller/TimeMapController.php
@@ -12,36 +12,59 @@ use OCP\AppFramework\Controller;
 use OCP\AppFramework\Http\DataDisplayResponse;
 
 class TimeMapController extends Controller {
-	private $userFolder;
-	private $URLGenerator;
+	use MementoFinder;
+
+	private $loggedInUserId;
+	private $serverContainer;
 
 	public function __construct(
 		$AppName,
 		IRequest $request,
 		$UserId,
-		IServerContainer $serverContainer,
-		IURLGenerator $URLGenerator
+		IServerContainer $serverContainer
 	) {
 		parent::__construct($AppName, $request);
-		$this->userFolder = $serverContainer->getUserFolder($UserId);
-		$this->URLGenerator = $URLGenerator;
+		$this->loggedInUserId = $UserId;
+		$this->serverContainer = $serverContainer;
 	}
 
 	/**
 	 * @NoAdminRequired
 	 * @NoCSRFRequired
+	 * @PublicPage
 	 */
-	public function timeMap($url) {
-		$url = getUrlParameter('timemap'); // XXX workaround, as nextcloud corrupts the $url parameter.
+	public function singleUserTimeMap($userId, $url) {
+		// XXX workaround, as nextcloud corrupts the $url parameter.
+		$routePrefix = "u/$userId/";
+		$url = getUrlParameter("{$routePrefix}timemap");
+
+		$matchingMementos = $this->findSingleUserMementosForUrl($userId, $url);
+
+		return $this->makeResponse($url, $matchingMementos, $routePrefix);
+	}
 
-		$matchingMementos = findMementos($this->userFolder, $url);
+	/**
+	 * @NoAdminRequired
+	 * @NoCSRFRequired
+	 * @PublicPage
+	 */
+	public function allUsersTimeMap($url) {
+		$routePrefix = "";
+		$url = getUrlParameter("{$routePrefix}timemap");
+
+		$matchingMementos = $this->findAllUsersMementosForUrl($url);
+
+		return $this->makeResponse($url, $matchingMementos, $routePrefix);
+	}
 
+	private function makeResponse($url, $matchingMementos, $routePrefix) {
 		// Build the list of links.
 		// $timeMapUrl = $this->URLGenerator->linkToRouteAbsolute('timeMap#timeMap', [ 'url' => $url ]);
 		// $timeGateUrl = $this->URLGenerator->linkToRouteAbsolute('timeGate#timeGate', [ 'url' => $url ]);
 		// FIXME ...is linkToRouteAbsolute broken? Hardcoding the path then..
-		$timeMapUrl = $this->URLGenerator->getAbsoluteUrl("/apps/memento/timemap/$url");
-		$timeGateUrl = $this->URLGenerator->getAbsoluteUrl("/apps/memento/timegate/$url");
+		$URLGenerator = $this->serverContainer->getURLGenerator();
+		$timeMapUrl = $URLGenerator->getAbsoluteUrl("/apps/memento/{$routePrefix}timemap/$url");
+		$timeGateUrl = $URLGenerator->getAbsoluteUrl("/apps/memento/{$routePrefix}timegate/$url");
 		if (count($matchingMementos) > 0) {
 			$firstDatetime = datetimeTimestampToString($matchingMementos[0]['datetime']);
 			$lastMemento = $matchingMementos[count($matchingMementos)-1];
@@ -58,7 +81,7 @@ class TimeMapController extends Controller {
 			$maybeFirst = $index === 0 ? 'first ' : '';
 			$maybeLast = $index === count($matchingMementos)-1 ? 'last ' : '';
 			// Make absolute, as the spec says URLs are to be interpreted relative to the *original* url!
-			$absoluteMementoUrl = $this->URLGenerator->getAbsoluteURL($memento['mementoUrl']);
+			$absoluteMementoUrl = $URLGenerator->getAbsoluteURL($memento['mementoUrl']);
 			$links[] = "<$absoluteMementoUrl>"
 				. ";rel=\"{$maybeFirst}{$maybeLast}memento\""
 				. ";datetime=\"$datetime\"";
diff --git a/lib/Controller/findMementos.php b/lib/Controller/findMementos.php
index 4d3a2d6..d52df21 100644
--- a/lib/Controller/findMementos.php
+++ b/lib/Controller/findMementos.php
@@ -1,61 +1,172 @@
 <?php
-use DOMDocument;
-use DateTime;
+namespace OCA\Memento\Controller;
+
+use \DOMDocument;
+use \DateTime;
+use OCP\Share;
+use OCP\Files\FileInfo;
 
 // Finds HTML files that claim to be a snapshot of the given URL;
 // Returns an array of mementos, sorted by datetime, with each memento represented by an array:
 // [
 //   'mementoUrl' => URL of the file, relative to the nextcloud instance
-//   'originalUrl' => original URL, presumably equal to the given $url, except we normalise a bit
+//   'originalUrls' => original URLs, usually just one.
 //   'datetime' => snapshot datetime as a unix timestamp
 // ]
-function findMementos($folder, $url) {
-	// Get all HTML files the user owns.
-	$files = $folder->searchByMime('text/html');
+//
+// Each mementoUrl is hardcoded to /apps/raw/..., thus relying on the 'raw' app to serve the files.
+
+trait MementoFinder {
+	function findSingleUserMementosForUrl($userId, $url) {
+		// Get the user's public mementos.
+		$foundMementos = findPublicMementos($this->serverContainer->getShareManager(), $userId);
+
+		// If logged in, and asking for one's own mementos, get private mementos too.
+		if ($this->loggedInUserId === $userId) {
+			$userFolder = $this->serverContainer->getUserFolder($this->loggedInUserId);
+			$moreMementos = findPrivateMementos($userFolder);
+			$foundMementos = mergeMementos($foundMementos, $moreMementos);
+		}
+
+		// Filter those that match the requested URL, and sort them.
+		$matchingMementos = filterMementosByUrl($foundMementos, $url);
+		sortMementos($matchingMementos);
+		return $matchingMementos;
+	}
+
+	function findAllUsersMementosForUrl($url) {
+		$foundMementos = [];
+
+		// Get the public mementos of every user.
+		$allUserIds = [];
+		$this->serverContainer->getUserManager()->callForAllUsers(
+			function ($user) use (&$allUserIds) { $allUserIds[] = $user->getUID(); }
+		);
+		$shareManager = $this->serverContainer->getShareManager();
+		foreach ($allUserIds as $userId) {
+			$moreMementos = findPublicMementos($shareManager, $userId);
+			$foundMementos = mergeMementos($foundMementos, $moreMementos);
+		}
+
+		// If logged in, get current user's private mementos too.
+		if ($this->loggedInUserId) {
+			$userFolder = $this->serverContainer->getUserFolder($this->loggedInUserId);
+			$moreMementos = findPrivateMementos($userFolder);
+			$foundMementos = mergeMementos($foundMementos, $moreMementos);
+		}
 
-	// Filter them for pages that have a <link rel="original"> referring to the given URL.
-	$matchingMementos = array();
+		// Filter those that match the requested URL, and sort them.
+		$matchingMementos = filterMementosByUrl($foundMementos, $url);
+		$matchingMementos = sortMementos($matchingMementos);
+		return $matchingMementos;
+	}
+}
+
+function findPrivateMementos($folder) {
+	$urlForFile = function ($file) use ($folder) {
+		$absoluteFilePath = $file->getPath();
+		$relativeFilePath = $folder->getRelativePath($absoluteFilePath);
+		$rawFileUrl = joinPaths("/apps/raw/files", $relativeFilePath); // XXX hardcoded dependency
+		return $rawFileUrl;
+	};
+
+	// Peek into each HTML file the user owns, and return those that are mementos.
+	$files = $folder->searchByMime('text/html');
+	$foundMementos = [];
 	foreach ($files as $file) {
-		$content = $file->getContent();
-		try {
-			$DOM = new DOMDocument;
-			$DOM->loadHTML($content);
-			$headElement = $DOM->documentElement->getElementsByTagName('head')[0];
-			$originalUrls = getOriginalUrls($headElement);
-			foreach ($originalUrls as $originalUrl) {
-				if (normaliseUrl($originalUrl) === normaliseUrl($url)) {
-					// Found a match!
-					// Read its datetime
-					$datetime = getDatetime($headElement);
-					// Construct its URL.
-					$absoluteFilePath = $file->getPath();
-					$relativeFilePath = $folder->getRelativePath($absoluteFilePath);
-					$mementoUrl = joinPaths("/apps/raw/files", $relativeFilePath); // XXX hardcoded dependency
-
-					$matchingMementos[] = [
-						'mementoUrl' =>  $mementoUrl,
-						'originalUrl' => $originalUrl,
-						'datetime' => $datetime
-					];
-				}
+		$mementoInfo = extractMementoInfo($file);
+		if ($mementoInfo) {
+			$mementoInfo['mementoUrl'] = $urlForFile($file);
+			$foundMementos[] = $mementoInfo;
+		}
+	}
+	return $foundMementos;
+}
+
+function findPublicMementos($shareManager, $userId) {
+	$shares = $shareManager->getSharesBy(
+		$userId,
+		Share::SHARE_TYPE_LINK,
+		null, /* path */
+		true, /* include reshares */
+		-1 /* no limit */
+	);
+
+	$urlForShare = function ($share) {
+		return "/apps/raw/s/" . $share->getToken(); // XXX hardcoded dependency
+	};
+
+	// Look into every shared file to see if it is a memento.
+	$foundMementos = [];
+	foreach ($shares as $share) {
+		$node = $share->getNode();
+		if ($node->getType() === FileInfo::TYPE_FILE) {
+			$mementoInfo = extractMementoInfo($node);
+			if ($mementoInfo) {
+				$mementoInfo['mementoUrl'] = $urlForShare($share);
+				$foundMementos[] = $mementoInfo;
 			}
-		} catch (Exception $e) {
-			continue;
+		} else {
+			// TODO add files inside shared folders? How to make URLs for those?
 		}
 	}
+	return $foundMementos;
+}
 
-	// Sort mementos by their datetime. Oldest first.
-	usort($matchingMementos, function ($m1, $m2) { return $m1['datetime'] <=> $m2['datetime']; });
+function mergeMementos($mementos1, $mementos2) {
+	// TODO deduplicate (we'll get public & private URLs for the same files)
+	return array_merge($mementos1, $mementos2);
+}
 
+function filterMementosByUrl($mementos, $url) {
+	$matchingMementos = array_filter($mementos, function ($mementoInfo) use ($url) {
+		return matchesUrl($mementoInfo, $url);
+	});
 	return $matchingMementos;
 }
 
+function matchesUrl($mementoInfo, $url) {
+	$originalUrls = $mementoInfo['originalUrls'];
+	foreach ($originalUrls as $originalUrl) {
+		if (normaliseUrl($originalUrl) === normaliseUrl($url)) {
+			return true;
+		}
+	}
+	return false;
+}
+
+function normaliseUrl($url) {
+	// Ignore trailing slashes. Because everybody does.
+	$url = rtrim($url, '/');
+	return $url;
+}
+
+// Sort an array of mementos by their datetime. Oldest first.
+function sortMementos($mementos) {
+	usort($mementos, function ($m1, $m2) { return $m1['datetime'] <=> $m2['datetime']; });
+	return $mementos;
+}
+
 function joinPaths($piece1, $piece2) {
 	$left = rtrim($piece1, '/');
 	$right = ltrim($piece2, '/');
 	return "$left/$right";
 }
 
+function extractMementoInfo($file) {
+	$content = $file->getContent();
+	$DOM = new DOMDocument;
+	$DOM->loadHTML($content);
+	$headElement = $DOM->documentElement->getElementsByTagName('head')[0];
+	if (!$headElement) return null; // possibly $content was not HTML at all.
+	$originalUrls = getOriginalUrls($headElement);
+	$datetime = getDatetime($headElement);
+	return [
+		'originalUrls' => $originalUrls,
+		'datetime' => $datetime
+	];
+}
+
 // Reads hrefs from any <link> with relation type "original".
 // (note the plural: we also accept pages that claim to correspond to multiple original URLs)
 function getOriginalUrls($headElement) {
@@ -87,9 +198,3 @@ function getDatetime($headElement) {
 	}
 	return null;
 }
-
-function normaliseUrl($url) {
-	// Ignore trailing slashes. Because everybody does.
-	$url = rtrim($url, '/');
-	return $url;
-}