diff --git a/utils/discovery.php b/utils/discovery.php
new file mode 100644
index 0000000..1cd8635
--- /dev/null
+++ b/utils/discovery.php
@@ -0,0 +1,180 @@
+<?php
+
+use Profile;
+
+/**
+ * GNU social - a federating social network
+ *
+ * ActivityPubPlugin implementation for GNU Social
+ *
+ * LICENCE: This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Daniel Supernault <danielsupernault@gmail.com>
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @copyright 2018 Free Software Foundation http://fsf.org
+ * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link      https://www.gnu.org/software/social/
+ */
+if (!defined ('GNUSOCIAL')) {
+        exit(1);
+}
+
+/**
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Daniel Supernault <danielsupernault@gmail.com>
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link      http://www.gnu.org/software/social/
+ */
+
+class Activitypub_Discovery
+{
+        private $discovered_actor_profiles = array ();
+
+        /**
+         * Get every profile from the given URL
+         * This function cleans the $this->discovered_actor_profiles array
+         * so that there is no erroneous data
+         *
+         * @param string $url User's url
+         * @return array of \Profile objects
+         */
+        public function lookup ($url)
+        {
+                $this->discovered_actor_profiles = array ();
+
+                return $this->_lookup ($url);
+        }
+
+        /**
+         * Get every profile from the given URL
+         * This is a recursive function that will accumulate the results on
+         * $discovered_actor_profiles array
+         *
+         * @param string $url User's url
+         * @return array of \Profile objects
+         */
+        private function _lookup ($url)
+        {
+                // First check if we already have it locally and, if so, return it
+                // If the local fetch fails: grab it remotely, store locally and return
+                $this->grab_local_user ($url) || $this->grab_remote_user($url);
+
+                return $this->discovered_actor_profiles;
+        }
+
+        /**
+         * Get a local user profiles from its URL and joins it on
+         * $this->discovered_actor_profiles
+         *
+         * @param string $url User's url
+         * @return boolean success state
+         */
+        private function grab_local_user ($url)
+        {
+                if (($actor_profile = Profile::getKV ("profileurl", $url)) != false) {
+                        $this->discovered_actor_profiles[]= $actor_profile;
+                        return true;
+                } else {
+                        /******************************** XXX: ********************************
+                         * Sometimes it is not true that the user is not locally available,   *
+                         * mostly when it is a local user and URLs slightly changed           *
+                         * e.g.: GS instance owner changed from standard urls to pretty urls  *
+                         * (not sure if this is necessary, but anyway)                        *
+                         **********************************************************************/
+
+                        // Iff we really are in the same instance
+                        $root_url_len = strlen (common_root_url ());
+                        if (substr ($url, 0, $root_url_len) == common_root_url ()) {
+                                // Grab the nickname and try to get the user
+                                if (($actor_profile = Profile::getKV ("nickname", substr ($url, $root_url_len))) != false) {
+                                        $this->discovered_actor_profiles[]= $actor_profile;
+                                        return true;
+                                }
+                        }
+                }
+                return false;
+        }
+
+        /**
+         * Get a remote user(s) profile(s) from its URL and joins it on
+         * $this->discovered_actor_profiles
+         *
+         * @param string $url User's url
+         * @return boolean success state
+         */
+        private function grab_remote_user ($url) {
+                $client    = new HTTPClient ();
+                $headers   = array();
+                $headers[] = 'Accept: application/ld+json; profile="https://www.w3.org/ns/activitystreams"';
+                $headers[] = 'User-Agent: GNUSocialBot v0.1 - https://gnu.io/social';
+                $response  = $client->get ($url, $headers);
+                if (!$response->isOk()) {
+                    throw new NoResultException ("Invalid Actor URL.");
+                }
+                $res = json_decode ($response->getBody (), JSON_UNESCAPED_SLASHES);
+                if (isset ($res["orderedItems"])) { // It's a potential collection of actors!!!
+                        foreach ($res["orderedItems"] as $profile) {
+                                if ($this->_lookup ($profile) == false) {
+                                        // XXX: Invalid actor found, not sure how we handle those
+                                }
+                        }
+                        // Go through entire collection
+                        if (!is_null ($res["next"])) {
+                                $this->_lookup ($res["next"]);
+                        }
+                        return true;
+                } else if ($this->validate_remote_response ($res)) {
+                        $this->discovered_actor_profiles[]= $this->store_profile ($res);
+                        return true;
+                }
+
+                return false;
+        }
+
+        /**
+         * Save remote user profile in local instance
+         *
+         * @param array $res remote response
+         * @return \Profile remote Profile object
+         */
+        private function store_profile ($res) {
+                $profile             = new Profile;
+                $profile->profileurl = $res["url"];
+                $profile->nickname   = $res["nickname"];
+                $profile->fullname   = $res["display_name"];
+                $profile->bio        = substr ($res["summary"], 0, 1000);
+                $profile->insert ();
+
+                return $profile;
+        }
+
+        /**
+         * Validates a remote response in order to determine whether this
+         * response is a valid profile or not
+         *
+         * @param array $res remote response
+         * @return boolean success state
+         */
+        private function validate_remote_response ($res) {
+                if (!isset ($res["url"], $res["nickname"], $res["display_name"], $res["summary"])) {
+                        return false;
+                }
+
+                return true;
+        }
+}