diff --git a/src/api/endpoints/i/appdata/get.ts b/src/api/endpoints/i/appdata/get.ts
index ccd8202531..47e1b8d202 100644
--- a/src/api/endpoints/i/appdata/get.ts
+++ b/src/api/endpoints/i/appdata/get.ts
@@ -1,6 +1,7 @@
 /**
  * Module dependencies
  */
+import $ from 'cafy';
 import Appdata from '../../../models/appdata';
 
 /**
@@ -14,10 +15,8 @@ import Appdata from '../../../models/appdata';
  */
 module.exports = (params, user, app, isSecure) => new Promise(async (res, rej) => {
 	// Get 'key' parameter
-	let key = params.key;
-	if (key === undefined) {
-		key = null;
-	}
+	const [key = null, keyError] = $(params.key).optional.nullable.string().match(/[a-z_]+/).$;
+	if (keyError) return rej('invalid key param');
 
 	if (isSecure) {
 		if (!user.data) {
@@ -38,7 +37,9 @@ module.exports = (params, user, app, isSecure) => new Promise(async (res, rej) =
 		const appdata = await Appdata.findOne({
 			app_id: app._id,
 			user_id: user._id
-		}, select);
+		}, {
+			fields: select
+		});
 
 		if (appdata) {
 			res(appdata.data);
diff --git a/src/api/endpoints/i/appdata/set.ts b/src/api/endpoints/i/appdata/set.ts
index 354935cb4c..6ba91cd804 100644
--- a/src/api/endpoints/i/appdata/set.ts
+++ b/src/api/endpoints/i/appdata/set.ts
@@ -1,6 +1,7 @@
 /**
  * Module dependencies
  */
+import $ from 'cafy';
 import Appdata from '../../../models/appdata';
 import User from '../../../models/user';
 import serialize from '../../../serializers/user';
@@ -16,17 +17,37 @@ import event from '../../../event';
  * @return {Promise<any>}
  */
 module.exports = (params, user, app, isSecure) => new Promise(async (res, rej) => {
-	const data = params.data;
-	if (data == null) {
-		return rej('data is required');
+	// Get 'set' parameter
+	const [set, setError] = $(params.set).optional.object()
+		.pipe(obj => {
+			return Object.entries(obj).some(kv => {
+				const k = kv[0];
+				const v = kv[1];
+				return $(k).string().match(/[a-z_]+/).isNg() && $(v).string().isNg();
+			});
+		}).$;
+	if (setError) return rej('invalid set param');
+
+	// Get 'key' parameter
+	const [key, keyError] = $(params.key).optional.string().match(/[a-z_]+/).$;
+	if (keyError) return rej('invalid key param');
+
+	// Get 'value' parameter
+	const [value, valueError] = $(params.value).optional.string().$;
+	if (valueError) return rej('invalid value param');
+
+	let data = {};
+	if (set) {
+		data = set;
+	} else {
+		data[key] = value;
 	}
 
 	if (isSecure) {
 		const _user = await User.findOneAndUpdate(user._id, {
-			$set: {
-				data: Object.assign(user.data || {}, JSON.parse(data))
-			}
+			$set: { data }
 		});
+
 		res(204);
 
 		// Publish i updated event
@@ -35,10 +56,6 @@ module.exports = (params, user, app, isSecure) => new Promise(async (res, rej) =
 			includeSecrets: true
 		}));
 	} else {
-		const appdata = await Appdata.findOne({
-			app_id: app._id,
-			user_id: user._id
-		});
 		await Appdata.update({
 			app_id: app._id,
 			user_id: user._id
@@ -46,12 +63,11 @@ module.exports = (params, user, app, isSecure) => new Promise(async (res, rej) =
 			app_id: app._id,
 			user_id: user._id
 		}, {
-			$set: {
-				data: Object.assign((appdata || {}).data || {}, JSON.parse(data))
-			}
+			$set: { data }
 		}), {
 			upsert: true
 		});
+
 		res(204);
 	}
 });