diff --git a/src/services/NotificationService.js b/src/services/NotificationService.js
index 027116d..9b5ea52 100644
--- a/src/services/NotificationService.js
+++ b/src/services/NotificationService.js
@@ -1,313 +1,360 @@
-/**
- * Service for notification functinoalities.
- */
-
-'use strict';
-
-const _ = require('lodash');
-const Joi = require('joi');
-const errors = require('../common/errors');
+/**
+ * Service for notification functinoalities.
+ */
+
+'use strict';
+
+const _ = require('lodash');
+const Joi = require('joi');
+const errors = require('../common/errors');
 const logger = require('../common/logger');
-const models = require('../models');
-
-const DEFAULT_LIMIT = 10;
-
-/**
- * Get notification settings.
- * @param {Number} userId the user id
- * @returns {Object} the notification settings
- */
-function* getSettings(userId) {
-  const notificationSettings = yield models.NotificationSetting.findAll({ where: { userId } });
-  const serviceSettings = yield models.ServiceSettings.findAll({ where: { userId } });
-
-  // format settings per notification type
-  const notifications = {};
-  _.each(notificationSettings, (setting) => {
-    if (!notifications[setting.topic]) {
-      notifications[setting.topic] = {};
-    }
-    if (!notifications[setting.topic][setting.serviceId]) {
-      notifications[setting.topic][setting.serviceId] = {};
-    }
-    notifications[setting.topic][setting.serviceId][setting.name] = setting.value;
-  });
-
-  // format settings per service
-  const services = {};
-  _.each(serviceSettings, (setting) => {
-    if (!services[setting.serviceId]) {
-      services[setting.serviceId] = {};
-    }
-    services[setting.serviceId][setting.name] = setting.value;
-  });
-  return {
-    notifications,
-    services,
-  };
-}
-
-getSettings.schema = {
-  userId: Joi.number().required(),
-};
-
-/**
- * Save notification setting entry. If the entry is not found, it will be created; otherwise it will be updated.
- * @param {Object} entry the notification setting entry
- * @param {Number} userId the user id
- */
-function* saveNotificationSetting(entry, userId) {
-  const setting = yield models.NotificationSetting.findOne({ where: {
-    userId, topic: entry.topic, serviceId: entry.serviceId, name: entry.name } });
-  if (setting) {
-    setting.value = entry.value;
-    yield setting.save();
-  } else {
-    yield models.NotificationSetting.create({
-      userId,
-      topic: entry.topic,
-      serviceId: entry.serviceId,
-      name: entry.name,
-      value: entry.value,
-    });
-  }
-}
-
-/**
- * Save service setting entry. If the entry is not found, it will be created; otherwise it will be updated.
- * @param {Object} entry the service setting entry
- * @param {Number} userId the user id
- */
-function* saveServiceSetting(entry, userId) {
-  const setting = yield models.ServiceSettings.findOne({ where: {
-    userId, serviceId: entry.serviceId, name: entry.name } });
-  if (setting) {
-    setting.value = entry.value;
-    yield setting.save();
-  } else {
-    yield models.ServiceSettings.create({
-      userId,
-      serviceId: entry.serviceId,
-      name: entry.name,
-      value: entry.value,
-    });
-  }
-}
-
-/**
- * Update notification settings. Un-specified settings are not changed.
- * @param {Array} data the notification settings data
- * @param {Number} userId the user id
- */
-function* updateSettings(data, userId) {
-  // convert notification settings object to the list of entries
-  const notifications = [];
-  _.forOwn(data.notifications, (notification, topic) => {
-    _.forOwn(notification, (serviceSettings, serviceId) => {
-      _.forOwn(serviceSettings, (value, name) => {
-        notifications.push({
-          topic,
-          serviceId,
-          name,
-          value,
-        });
-      });
-    });
-  });
-
-  // validation
-  // there should be no duplicate (topic + serviceId + name)
-  const triples = {};
-  notifications.forEach((entry) => {
-    const key = `${entry.topic} | ${entry.serviceId} | ${entry.name}`;
-    if (triples[key]) {
-      throw new errors.BadRequestError(`There are duplicate data for topic: ${
-        entry.topic}, serviceId: ${entry.serviceId}, name: ${entry.name}`);
-    }
-    triples[key] = entry;
-  });
-
-  // save each entry in parallel
-  yield _.map(notifications, (entry) => saveNotificationSetting(entry, userId));
-
-  // convert services settings object the the list of entries
-  const services = [];
-  _.forOwn(data.services, (service, serviceId) => {
-    _.forOwn(service, (value, name) => {
-      services.push({
-        serviceId,
-        name,
-        value,
-      });
-    });
-  });
-
-  // validation
-  // there should be no duplicate (serviceId + name)
-  const paris = {};
-  services.forEach((entry) => {
-    const key = `${entry.serviceId} | ${entry.name}`;
-    if (paris[key]) {
-      throw new errors.BadRequestError('There are duplicate data for'
-        + ` serviceId: ${entry.serviceId}, name: ${entry.name}`);
-    }
-    paris[key] = entry;
-  });
-
-  yield _.map(services, (entry) => saveServiceSetting(entry, userId));
-}
-
-updateSettings.schema = {
-  data: Joi.object().keys({
-    notifications: Joi.object(),
-    services: Joi.object(),
-  }).required(),
-  userId: Joi.number().required(),
-};
-
-/**
- * List notifications.
- *
- * This method returns only notifications for 'web'
- * Also this method filters notifications by the user and filters out notifications,
- * which user disabled in his settings.
- *
- * @param {Object} query the query parameters
- * @param {Number} userId the user id
- * @returns {Object} the search result
- */
-function* listNotifications(query, userId) {
-  const settings = yield getSettings(userId);
-  const notificationSettings = settings.notifications;
-
-  const filter = { where: {
-    userId,
-  }, offset: query.offset, limit: query.limit, order: [['createdAt', 'DESC']] };
-  if (_.keys(notificationSettings).length > 0) {
-    // only filter out notifications types which were explicitly set to 'no' - so we return notification by default
-    const notifications = _.keys(notificationSettings).filter((notificationType) =>
-      !notificationSettings[notificationType] &&
-      !notificationSettings[notificationType].web &&
-      notificationSettings[notificationType].web.enabled === 'no'
-    );
-    filter.where.type = { $notIn: notifications };
-  }
-  if (query.type) {
-    filter.where.type = query.type;
-  }
-  if (query.read) {
-    filter.where.read = (query.read === 'true');
-  }
-  const docs = yield models.Notification.findAndCountAll(filter);
-  const items = _.map(docs.rows, r => {
-    const item = r.toJSON();
-    // id and userId are BIGINT in database, sequelize maps them to string values,
-    // convert them back to Number values
-    item.id = Number(item.id);
-    item.userId = Number(item.userId);
-    return item;
-  });
-  return {
-    items,
-    offset: query.offset,
-    limit: query.limit,
-    totalCount: docs.count,
-  };
-}
-
-listNotifications.schema = {
-  query: Joi.object().keys({
-    offset: Joi.number().integer().min(0).default(0),
-    limit: Joi.number().integer().min(1).default(DEFAULT_LIMIT),
-    type: Joi.string(),
-    // when it is true, return only read notifications
-    // when it is false, return only un-read notifications
-    // when it is no provided, no read flag filtering
-    read: Joi.string().valid('true', 'false'),
-  }).required(),
-  userId: Joi.number().required(),
-};
-
-/**
- * Mark notification(s) as read.
- * @param {Number} id the notification id or '-' separated ids
- * @param {Number} userId the user id
- */
-function* markAsRead(id, userId) {
-  const ids = _.map(id.split('-'), (str) => {
-    const idInt = Number(str);
-    if (!_.isInteger(idInt)) {
-      throw new errors.BadRequestError(`Notification id should be integer: ${str}`);
-    }
-    return idInt;
-  });
-  const entities = yield models.Notification.findAll({ where: { id: { $in: ids }, read: false } });
-  if (!entities || entities.length === 0) {
-    throw new errors.NotFoundError(`Cannot find un-read Notification where id = ${id}`);
-  }
-  _.each(entities, (entity) => {
-    if (Number(entity.userId) !== userId) {
-      throw new errors.ForbiddenError(`Cannot access Notification where id = ${entity.id}`);
-    }
-  });
-  yield models.Notification.update({ read: true }, { where: { id: { $in: ids }, read: false } });
-}
-
-markAsRead.schema = {
-  id: Joi.string().required(),
-  userId: Joi.number().required(),
-};
-
-/**
- * Mark all notifications as read.
- * @param {Number} userId the user id
- */
-function* markAllRead(userId) {
-  yield models.Notification.update({ read: true }, { where: { userId, read: false } });
-}
-
-markAllRead.schema = {
-  userId: Joi.number().required(),
-};
-
-/**
- * Mark notification(s) as seen.
- * @param {Number} id the notification id or '-' separated ids
- * @param {Number} userId the user id
- */
-function* markAsSeen(id, userId) {
-  const ids = _.map(id.split('-'), (str) => {
-    const idInt = Number(str);
-    if (!_.isInteger(idInt)) {
-      throw new errors.BadRequestError(`Notification id should be integer: ${str}`);
-    }
-    return idInt;
-  });
-  const entities = yield models.Notification.findAll({ where: { id: { $in: ids }, seen: { $not: true } } });
-  if (!entities || entities.length === 0) {
-    throw new errors.NotFoundError(`Cannot find un-seen Notification where id = ${id}`);
-  }
-  _.each(entities, (entity) => {
-    if (Number(entity.userId) !== userId) {
-      throw new errors.ForbiddenError(`Cannot access Notification where id = ${entity.id}`);
-    }
-  });
-  yield models.Notification.update({ seen: true }, { where: { id: { $in: ids }, seen: { $not: true } } });
-}
-
-markAsSeen.schema = {
-  id: Joi.string().required(),
-  userId: Joi.number().required(),
-};
-
-// Exports
-module.exports = {
-  listNotifications,
-  markAsRead,
-  markAllRead,
-  markAsSeen,
-  getSettings,
-  updateSettings,
-};
+const models = require('../models');
+
+const DEFAULT_LIMIT = 10;
+
+/**
+ * Get notification settings.
+ * @param {Number} userId the user id
+ * @returns {Object} the notification settings
+ */
+function* getSettings(userId) {
+  const notificationSettings = yield models.NotificationSetting.findAll({ where: { userId } });
+  const serviceSettings = yield models.ServiceSettings.findAll({ where: { userId } });
+
+  // format settings per notification type
+  const notifications = {};
+  _.each(notificationSettings, (setting) => {
+    if (!notifications[setting.topic]) {
+      notifications[setting.topic] = {};
+    }
+    if (!notifications[setting.topic][setting.serviceId]) {
+      notifications[setting.topic][setting.serviceId] = {};
+    }
+    notifications[setting.topic][setting.serviceId][setting.name] = setting.value;
+  });
+
+  // format settings per service
+  const services = {};
+  _.each(serviceSettings, (setting) => {
+    if (!services[setting.serviceId]) {
+      services[setting.serviceId] = {};
+    }
+    services[setting.serviceId][setting.name] = setting.value;
+  });
+  return {
+    notifications,
+    services,
+  };
+}
+
+getSettings.schema = {
+  userId: Joi.number().required(),
+};
+
+/**
+ * Save notification setting entry. If the entry is not found, it will be created; otherwise it will be updated.
+ * @param {Object} entry the notification setting entry
+ * @param {Number} userId the user id
+ */
+function* saveNotificationSetting(entry, userId) {
+  const setting = yield models.NotificationSetting.findOne({ where: {
+    userId, topic: entry.topic, serviceId: entry.serviceId, name: entry.name } });
+  if (setting) {
+    setting.value = entry.value;
+    yield setting.save();
+  } else {
+    yield models.NotificationSetting.create({
+      userId,
+      topic: entry.topic,
+      serviceId: entry.serviceId,
+      name: entry.name,
+      value: entry.value,
+    });
+  }
+}
+
+/**
+ * Save service setting entry. If the entry is not found, it will be created; otherwise it will be updated.
+ * @param {Object} entry the service setting entry
+ * @param {Number} userId the user id
+ */
+function* saveServiceSetting(entry, userId) {
+  const setting = yield models.ServiceSettings.findOne({ where: {
+    userId, serviceId: entry.serviceId, name: entry.name } });
+  if (setting) {
+    setting.value = entry.value;
+    yield setting.save();
+  } else {
+    yield models.ServiceSettings.create({
+      userId,
+      serviceId: entry.serviceId,
+      name: entry.name,
+      value: entry.value,
+    });
+  }
+}
+
+/**
+ * Update notification settings. Un-specified settings are not changed.
+ * @param {Array} data the notification settings data
+ * @param {Number} userId the user id
+ */
+function* updateSettings(data, userId) {
+  // convert notification settings object to the list of entries
+  const notifications = [];
+  _.forOwn(data.notifications, (notification, topic) => {
+    _.forOwn(notification, (serviceSettings, serviceId) => {
+      _.forOwn(serviceSettings, (value, name) => {
+        notifications.push({
+          topic,
+          serviceId,
+          name,
+          value,
+        });
+      });
+    });
+  });
+
+  // validation
+  // there should be no duplicate (topic + serviceId + name)
+  const triples = {};
+  notifications.forEach((entry) => {
+    const key = `${entry.topic} | ${entry.serviceId} | ${entry.name}`;
+    if (triples[key]) {
+      throw new errors.BadRequestError(`There are duplicate data for topic: ${
+        entry.topic}, serviceId: ${entry.serviceId}, name: ${entry.name}`);
+    }
+    triples[key] = entry;
+  });
+
+  // save each entry in parallel
+  yield _.map(notifications, (entry) => saveNotificationSetting(entry, userId));
+
+  // convert services settings object the the list of entries
+  const services = [];
+  _.forOwn(data.services, (service, serviceId) => {
+    _.forOwn(service, (value, name) => {
+      services.push({
+        serviceId,
+        name,
+        value,
+      });
+    });
+  });
+
+  // validation
+  // there should be no duplicate (serviceId + name)
+  const paris = {};
+  services.forEach((entry) => {
+    const key = `${entry.serviceId} | ${entry.name}`;
+    if (paris[key]) {
+      throw new errors.BadRequestError('There are duplicate data for'
+        + ` serviceId: ${entry.serviceId}, name: ${entry.name}`);
+    }
+    paris[key] = entry;
+  });
+
+  yield _.map(services, (entry) => saveServiceSetting(entry, userId));
+}
+
+updateSettings.schema = {
+  data: Joi.object().keys({
+    notifications: Joi.object(),
+    services: Joi.object(),
+  }).required(),
+  userId: Joi.number().required(),
+};
+
+/**
+ * List notifications.
+ *
+ * This method returns only notifications for 'web'
+ * Also this method filters notifications by the user and filters out notifications,
+ * which user disabled in his settings.
+ *
+ * @param {Object} query the query parameters
+ * @param {Number} userId the user id
+ * @returns {Object} the search result
+ */
+function* listNotifications(query, userId) {
+  const settings = yield getSettings(userId);
+  const notificationSettings = settings.notifications;
+  const limit = query.limit || query.per_page;
+  const offset = (query.page - 1) * limit;
+  const filter = { where: {
+    userId,
+  }, offset, limit, order: [['createdAt', 'DESC']] };
+  if (query.platform) {
+    filter.where.type = { $like: `notifications\.${query.platform}\.%` };
+  }
+  if (_.keys(notificationSettings).length > 0) {
+    // only filter out notifications types which were explicitly set to 'no' - so we return notification by default
+    const notifications = _.keys(notificationSettings).filter((notificationType) =>
+      !notificationSettings[notificationType] &&
+      !notificationSettings[notificationType].web &&
+      notificationSettings[notificationType].web.enabled === 'no'
+    );
+    filter.where.type = Object.assign(filter.where.type || {}, { $notIn: notifications });
+  }
+  if (query.type) {
+    filter.where.type = Object.assign(filter.where.type || {}, { $eq: query.type });
+  }
+  if (query.read) {
+    filter.where.read = (query.read === 'true');
+  }
+  const docs = yield models.Notification.findAndCountAll(filter);
+  const items = _.map(docs.rows, r => {
+    const item = r.toJSON();
+    // id and userId are BIGINT in database, sequelize maps them to string values,
+    // convert them back to Number values
+    item.id = Number(item.id);
+    item.userId = Number(item.userId);
+    return item;
+  });
+  return {
+    items,
+    perPage: limit,
+    currentPage: query.page,
+    total: docs.count,
+  };
+}
+
+listNotifications.schema = {
+  query: Joi.object().keys({
+    page: Joi.number().integer().min(1).default(1),
+    per_page: Joi.number().integer().min(1).default(DEFAULT_LIMIT),
+    // supporting limit field temporarily
+    limit: Joi.number().integer().min(1),
+    type: Joi.string(),
+    platform: Joi.string(),
+    // when it is true, return only read notifications
+    // when it is false, return only un-read notifications
+    // when it is no provided, no read flag filtering
+    read: Joi.string().valid('true', 'false'),
+  }).required(),
+  userId: Joi.number().required(),
+};
+
+/**
+ * Update notification.
+ *
+ * Update notification based on notification id
+ *
+ * @param {Number} userId the user id
+ * @param {Number} notificationId the notification id
+ * @param {Object} payload the update notification payload
+ * @returns {Object} the updated notification
+ */
+function* updateNotification(userId, notificationId, payload) {
+  if (payload.read === false) {
+    throw new errors.ValidationError('Cannot set notification to be unread');
+  }
+  if (payload.seen === false) {
+    throw new errors.ValidationError('Cannot set notification to be unseen');
+  }
+
+  const entity = yield models.Notification.findOne({ where: { id: Number(notificationId) } });
+  if (!entity) {
+    throw new errors.NotFoundError(`Cannot find Notification where id = ${notificationId}`);
+  }
+  if (Number(entity.userId) !== userId) {
+    throw new errors.ForbiddenError(`Cannot access Notification where id = ${entity.id}`);
+  }
+  yield models.Notification.update(payload, { where: { id: Number(notificationId), userId: Number(userId) } });
+
+  return Object.assign(entity, payload);
+}
+
+updateNotification.schema = {
+  userId: Joi.number().required(),
+  notificationId: Joi.number().required(),
+  payload: Joi.object().keys({
+    read: Joi.boolean(),
+    seen: Joi.boolean(),
+  }),
+};
+
+/**
+ * Mark notification(s) as read.
+ * @param {Number} id the notification id or '-' separated ids
+ * @param {Number} userId the user id
+ */
+function* markAsRead(id, userId) {
+  const ids = _.map(id.split('-'), (str) => {
+    const idInt = Number(str);
+    if (!_.isInteger(idInt)) {
+      throw new errors.BadRequestError(`Notification id should be integer: ${str}`);
+    }
+    return idInt;
+  });
+  const entities = yield models.Notification.findAll({ where: { id: { $in: ids }, read: false } });
+  if (!entities || entities.length === 0) {
+    throw new errors.NotFoundError(`Cannot find un-read Notification where id = ${id}`);
+  }
+  _.each(entities, (entity) => {
+    if (Number(entity.userId) !== userId) {
+      throw new errors.ForbiddenError(`Cannot access Notification where id = ${entity.id}`);
+    }
+  });
+  yield models.Notification.update({ read: true }, { where: { id: { $in: ids }, read: false } });
+}
+
+markAsRead.schema = {
+  id: Joi.string().required(),
+  userId: Joi.number().required(),
+};
+
+/**
+ * Mark all notifications as read.
+ * @param {Number} userId the user id
+ */
+function* markAllRead(userId) {
+  yield models.Notification.update({ read: true }, { where: { userId, read: false } });
+}
+
+markAllRead.schema = {
+  userId: Joi.number().required(),
+};
+
+/**
+ * Mark notification(s) as seen.
+ * @param {Number} id the notification id or '-' separated ids
+ * @param {Number} userId the user id
+ */
+function* markAsSeen(id, userId) {
+  const ids = _.map(id.split('-'), (str) => {
+    const idInt = Number(str);
+    if (!_.isInteger(idInt)) {
+      throw new errors.BadRequestError(`Notification id should be integer: ${str}`);
+    }
+    return idInt;
+  });
+  const entities = yield models.Notification.findAll({ where: { id: { $in: ids }, seen: { $not: true } } });
+  if (!entities || entities.length === 0) {
+    throw new errors.NotFoundError(`Cannot find un-seen Notification where id = ${id}`);
+  }
+  _.each(entities, (entity) => {
+    if (Number(entity.userId) !== userId) {
+      throw new errors.ForbiddenError(`Cannot access Notification where id = ${entity.id}`);
+    }
+  });
+  yield models.Notification.update({ seen: true }, { where: { id: { $in: ids }, seen: { $not: true } } });
+}
+
+markAsSeen.schema = {
+  id: Joi.string().required(),
+  userId: Joi.number().required(),
+};
+
+// Exports
+module.exports = {
+  listNotifications,
+  markAsRead,
+  markAllRead,
+  markAsSeen,
+  getSettings,
+  updateSettings,
+  updateNotification,
+};
 
 logger.buildService(module.exports);