diff --git a/lib/ImportExport/OPML.php b/lib/ImportExport/OPML.php
new file mode 100644
index 0000000..e3053a0
--- /dev/null
+++ b/lib/ImportExport/OPML.php
@@ -0,0 +1,59 @@
+<?php
+/** @license MIT
+ * Copyright 2017 J. King, Dustin Wilson et al.
+ * See LICENSE and AUTHORS files for details */
+
+declare(strict_types=1);
+namespace JKingWeb\Arsse\ImportExport;
+
+use JKingWeb\Arsse\Arsse;
+
+class OPML {
+    public function export(string $user, bool $flat = false): string {
+        $folders = [];
+        $parents = [0 => null];
+        $tags = [];
+        $document = new \DOMDocument("1.0", "utf-8");
+        $document->formatOutput = true;
+        $document->appendChild($document->createElement("opml"));
+        $document->documentElement->setAttribute("version", "2.0");
+        $document->documentElement->appendChild($document->createElement("head"));
+        // create the "root folder" node (the body node, in OPML terms)
+        $folders[0] = $document->createElement("body");
+        $transaction = Arsse::$db->begin();
+        foreach (Arsse::$db->tagSummarize($user) as $r) {
+            $sub = $r['subscription'];
+            $tag = $r['name'];
+            $tag = str_replace(",", "", $tag);
+            if (!isset($tags[$sub])) {
+                $tags[$sub] = [];
+            }
+            $tags[$sub][] = $tag;
+        }
+        if (!$flat) {
+            foreach (Arsse::$db->folderList($user) as $r) {
+                $parents[$r['id']] = $r['parent'] ?? 0;
+                $el = $document->createElement("outline");
+                $el->setAttribute("text", $r['name']);
+                $folders[$r['id']] = $el;
+            }
+        }
+        foreach (Arsse::$db->subscriptionList($user) as $r) {
+            $el = $document->createElement(("outline"));
+            $el->setAttribute("text", $r['title']);
+            $el->setAttribute("type", "rss");
+            $el->setAttribute("xmlUrl", $r['url']);
+            if (sizeof($tags[$r['id']])) {
+                $el->setAttribute("category", implode(",", $tags[$r['id']]));
+            }
+            ($folders[$r['folder'] ?? 0] ?? $folders[0])->appendChild($el);
+        }
+        $transaction->rollback();
+        foreach ($folders as $id => $el) {
+            $parent = $parents[$id] ?? $document->documentElement;
+            $parent->appendChild($el);
+        }
+        // return the serialization
+        return $document->saveXML();
+    }
+}