diff --git a/packages/backend/src/apps/firebase/authentication.ts b/packages/backend/src/apps/firebase/authentication.ts
index 03f9ff82..31a872ea 100644
--- a/packages/backend/src/apps/firebase/authentication.ts
+++ b/packages/backend/src/apps/firebase/authentication.ts
@@ -1,10 +1,14 @@
+import AuthenticationInterface from '../../types/interfaces/authentication-interface';
 import { google as GoogleApi } from 'googleapis';
+import { OAuth2Client } from 'google-auth-library';
 import Field from '../../types/field';
+import AppInfo from '../../types/app-info';
+import JSONObject from '../../types/interfaces/json-object';
 
-export default class Authentication {
-  appData: any;
-  connectionData: any;
-  client: any;
+export default class Authentication implements AuthenticationInterface {
+  appData: AppInfo;
+  connectionData: JSONObject;
+  client: OAuth2Client;
 
   scopes: string[] = [
     'https://www.googleapis.com/auth/datastore',
@@ -13,13 +17,13 @@ export default class Authentication {
     'profile',
   ];
 
-  constructor(appData: any, connectionData: any) {
+  constructor(appData: AppInfo, connectionData: JSONObject) {
     this.appData = appData;
     this.connectionData = connectionData;
 
     this.client = new GoogleApi.auth.OAuth2(
-      connectionData.consumerKey,
-      connectionData.consumerSecret,
+      connectionData.consumerKey as string,
+      connectionData.consumerSecret as string,
       this.oauthRedirectUrl
     );
 
@@ -43,7 +47,7 @@ export default class Authentication {
 
   async verifyCredentials() {
     const { tokens } = await this.client.getToken(
-      this.connectionData.oauthVerifier
+      this.connectionData.oauthVerifier as string
     );
     this.client.setCredentials(tokens);
 
@@ -74,7 +78,7 @@ export default class Authentication {
 
   async isStillVerified() {
     try {
-      await this.client.getTokenInfo(this.connectionData.accessToken);
+      await this.client.getTokenInfo(this.connectionData.accessToken as string);
       return true;
     } catch {
       return false;
diff --git a/packages/backend/src/apps/flickr/authentication.ts b/packages/backend/src/apps/flickr/authentication.ts
index 4466384f..890d5d31 100644
--- a/packages/backend/src/apps/flickr/authentication.ts
+++ b/packages/backend/src/apps/flickr/authentication.ts
@@ -1,13 +1,16 @@
+import AuthenticationInterface from '../../types/interfaces/authentication-interface';
 import FlickrApi from 'flickr-sdk';
+import AppInfo from '../../types/app-info';
 import Field from '../../types/field';
+import JSONObject from '../../types/interfaces/json-object';
 
-export default class Authentication {
-  appData: any;
-  connectionData: any;
-  client: any;
-  oauthClient: any;
+export default class Authentication implements AuthenticationInterface {
+  appData: AppInfo;
+  connectionData: JSONObject;
+  client: typeof FlickrApi;
+  oauthClient: typeof FlickrApi;
 
-  constructor(appData: any, connectionData: any) {
+  constructor(appData: AppInfo, connectionData: JSONObject) {
     this.oauthClient = new FlickrApi.OAuth(
       connectionData.consumerKey,
       connectionData.consumerSecret
diff --git a/packages/backend/src/apps/flickr/index.d.ts b/packages/backend/src/apps/flickr/types/index.d.ts
similarity index 100%
rename from packages/backend/src/apps/flickr/index.d.ts
rename to packages/backend/src/apps/flickr/types/index.d.ts
diff --git a/packages/backend/src/apps/github/authentication.ts b/packages/backend/src/apps/github/authentication.ts
index e51ebd1e..23a417b8 100644
--- a/packages/backend/src/apps/github/authentication.ts
+++ b/packages/backend/src/apps/github/authentication.ts
@@ -1,18 +1,32 @@
+import AuthenticationInterface from '../../types/interfaces/authentication-interface';
 import {
   getWebFlowAuthorizationUrl,
   exchangeWebFlowCode,
   checkToken,
 } from '@octokit/oauth-methods';
+import AppInfo from '../../types/app-info';
 import Field from '../../types/field';
+import JSONObject from '../../types/interfaces/json-object';
 
-export default class Authentication {
-  appData: any;
-  connectionData: any;
+export default class Authentication implements AuthenticationInterface {
+  appData: AppInfo;
+  connectionData: JSONObject;
   scopes: string[] = ['repo'];
+  client: {
+    getWebFlowAuthorizationUrl: typeof getWebFlowAuthorizationUrl;
+    exchangeWebFlowCode: typeof exchangeWebFlowCode;
+    checkToken: typeof checkToken;
+  };
 
-  constructor(appData: any, connectionData: any) {
+  constructor(appData: AppInfo, connectionData: JSONObject) {
     this.connectionData = connectionData;
     this.appData = appData;
+
+    this.client = {
+      getWebFlowAuthorizationUrl,
+      exchangeWebFlowCode,
+      checkToken,
+    };
   }
 
   get oauthRedirectUrl(): string {
@@ -21,10 +35,10 @@ export default class Authentication {
     ).value;
   }
 
-  async createAuthData(): { url: string } {
-    const { url } = await getWebFlowAuthorizationUrl({
+  async createAuthData(): Promise<{ url: string }> {
+    const { url } = await this.client.getWebFlowAuthorizationUrl({
       clientType: 'oauth-app',
-      clientId: this.connectionData.consumerKey,
+      clientId: this.connectionData.consumerKey as string,
       redirectUrl: this.oauthRedirectUrl,
       scopes: this.scopes,
     });
@@ -34,12 +48,12 @@ export default class Authentication {
     };
   }
 
-  async verifyCredentials(): any {
-    const { data } = await exchangeWebFlowCode({
+  async verifyCredentials() {
+    const { data } = await this.client.exchangeWebFlowCode({
       clientType: 'oauth-app',
-      clientId: this.connectionData.consumerKey,
-      clientSecret: this.connectionData.consumerSecret,
-      code: this.connectionData.oauthVerifier,
+      clientId: this.connectionData.consumerKey as string,
+      clientSecret: this.connectionData.consumerSecret as string,
+      code: this.connectionData.oauthVerifier as string,
     });
 
     this.connectionData.accessToken = data.access_token;
@@ -58,15 +72,15 @@ export default class Authentication {
   }
 
   async getTokenInfo() {
-    return checkToken({
+    return this.client.checkToken({
       clientType: 'oauth-app',
-      clientId: this.connectionData.consumerKey,
-      clientSecret: this.connectionData.consumerSecret,
-      token: this.connectionData.accessToken,
+      clientId: this.connectionData.consumerKey as string,
+      clientSecret: this.connectionData.consumerSecret as string,
+      token: this.connectionData.accessToken as string,
     });
   }
 
-  async isStillVerified(): boolean {
+  async isStillVerified() {
     try {
       await this.getTokenInfo();
 
diff --git a/packages/backend/src/apps/postgresql/authentication.ts b/packages/backend/src/apps/postgresql/authentication.ts
index 677ce570..a45e3543 100644
--- a/packages/backend/src/apps/postgresql/authentication.ts
+++ b/packages/backend/src/apps/postgresql/authentication.ts
@@ -1,18 +1,21 @@
+import AuthenticationInterface from '../../types/interfaces/authentication-interface';
 import { Client } from 'pg';
+import AppInfo from '../../types/app-info';
+import JSONObject from '../../types/interfaces/json-object';
 
-export default class Authentication {
-  appData: any;
-  connectionData: any;
-  client: any;
+export default class Authentication implements AuthenticationInterface {
+  appData: AppInfo;
+  connectionData: JSONObject;
+  client: Client;
 
-  constructor(appData: any, connectionData: any) {
+  constructor(appData: AppInfo, connectionData: JSONObject) {
     this.client = new Client({
-      host: connectionData.host,
-      port: connectionData.port,
-      database: connectionData.database,
-      user: connectionData.username,
-      password: connectionData.password,
-      ssl: connectionData.ssl,
+      host: connectionData.host as string,
+      port: connectionData.port as number,
+      database: connectionData.database as string,
+      user: connectionData.username as string,
+      password: connectionData.password as string,
+      ssl: connectionData.ssl as boolean,
     });
 
     this.connectionData = connectionData;
diff --git a/packages/backend/src/apps/smtp/authentication.ts b/packages/backend/src/apps/smtp/authentication.ts
index b217e54e..5ade97b6 100644
--- a/packages/backend/src/apps/smtp/authentication.ts
+++ b/packages/backend/src/apps/smtp/authentication.ts
@@ -1,11 +1,13 @@
-import nodemailer from 'nodemailer';
+import nodemailer, { Transporter, TransportOptions } from 'nodemailer';
+import AppInfo from '../../types/app-info';
+import JSONObject from '../../types/interfaces/json-object';
 
 export default class Authentication {
-  appData: any;
-  connectionData: any;
-  client: any;
+  appData: AppInfo;
+  connectionData: JSONObject;
+  client: Transporter;
 
-  constructor(appData: any, connectionData: any) {
+  constructor(appData: AppInfo, connectionData: JSONObject) {
     this.client = nodemailer.createTransport({
       host: connectionData.host,
       port: connectionData.port,
@@ -14,7 +16,7 @@ export default class Authentication {
         user: connectionData.username,
         pass: connectionData.password,
       },
-    });
+    } as TransportOptions);
 
     this.connectionData = connectionData;
     this.appData = appData;
diff --git a/packages/backend/src/apps/twilio/authentication.ts b/packages/backend/src/apps/twilio/authentication.ts
index ba28fc16..bff16c3a 100644
--- a/packages/backend/src/apps/twilio/authentication.ts
+++ b/packages/backend/src/apps/twilio/authentication.ts
@@ -1,14 +1,17 @@
+import AuthenticationInterface from '../../types/interfaces/authentication-interface';
 import TwilioApi from 'twilio';
+import AppInfo from '../../types/app-info';
+import JSONObject from '../../types/interfaces/json-object';
 
-export default class Authentication {
-  appData: any;
-  connectionData: any;
-  client: any;
+export default class Authentication implements AuthenticationInterface {
+  appData: AppInfo;
+  connectionData: JSONObject;
+  client: TwilioApi.Twilio;
 
-  constructor(appData: any, connectionData: any) {
+  constructor(appData: AppInfo, connectionData: JSONObject) {
     this.client = TwilioApi(
-      connectionData.accountSid,
-      connectionData.authToken
+      connectionData.accountSid as string,
+      connectionData.authToken as string
     );
 
     this.connectionData = connectionData;
diff --git a/packages/backend/src/apps/twitch/authentication.ts b/packages/backend/src/apps/twitch/authentication.ts
index a7c451d9..862724b4 100644
--- a/packages/backend/src/apps/twitch/authentication.ts
+++ b/packages/backend/src/apps/twitch/authentication.ts
@@ -1,6 +1,9 @@
-import TwitchApi from 'twitch-js';
+import AuthenticationInterface from '../../types/interfaces/authentication-interface';
+import TwitchApi, { TwitchJsOptions } from 'twitch-js';
 import fetchUtil from 'twitch-js/lib/utils/fetch';
+import AppInfo from '../../types/app-info';
 import Field from '../../types/field';
+import JSONObject from '../../types/interfaces/json-object';
 
 type TwitchTokenResponse = {
   accessToken: string;
@@ -9,17 +12,17 @@ type TwitchTokenResponse = {
   tokenType: string;
 };
 
-export default class Authentication {
-  appData: any;
-  connectionData: any;
-  client: any;
+export default class Authentication implements AuthenticationInterface {
+  appData: AppInfo;
+  connectionData: JSONObject;
+  client: TwitchApi;
 
-  constructor(appData: any, connectionData: any) {
+  constructor(appData: AppInfo, connectionData: JSONObject) {
     this.connectionData = connectionData;
     this.appData = appData;
 
     if (this.clientOptions.token) {
-      this.client = new TwitchApi(this.clientOptions);
+      this.client = new TwitchApi(this.clientOptions as TwitchJsOptions);
     }
   }
 
@@ -67,7 +70,7 @@ export default class Authentication {
 
     this.connectionData.accessToken = verifiedCredentials.accessToken;
 
-    const { api } = new TwitchApi(this.clientOptions);
+    const { api } = new TwitchApi(this.clientOptions as TwitchJsOptions);
 
     const { data } = await api.get('users');
     const [user] = data;
diff --git a/packages/backend/src/apps/twitter/authentication.ts b/packages/backend/src/apps/twitter/authentication.ts
index d596ff8c..54bab8ce 100644
--- a/packages/backend/src/apps/twitter/authentication.ts
+++ b/packages/backend/src/apps/twitter/authentication.ts
@@ -1,21 +1,26 @@
-import TwitterApi from 'twitter-api-v2';
+import AuthenticationInterface from '../../types/interfaces/authentication-interface';
+import TwitterApi, { TwitterApiTokens } from 'twitter-api-v2';
+import AppInfo from '../../types/app-info';
 import Field from '../../types/field';
+import JSONObject from '../../types/interfaces/json-object';
 
-export default class Authentication {
-  appData: any;
-  connectionData: any;
-  client: any;
+export default class Authentication implements AuthenticationInterface {
+  appData: AppInfo;
+  connectionData: JSONObject;
+  client: TwitterApi;
 
-  constructor(appData: any, connectionData: any) {
+  constructor(appData: AppInfo, connectionData: JSONObject) {
     this.appData = appData;
     this.connectionData = connectionData;
 
-    this.client = new TwitterApi({
+    const clientParams = {
       appKey: connectionData.consumerKey,
       appSecret: connectionData.consumerSecret,
       accessToken: connectionData.accessToken,
       accessSecret: connectionData.accessSecret,
-    });
+    } as TwitterApiTokens;
+
+    this.client = new TwitterApi(clientParams);
   }
 
   async createAuthData() {
@@ -35,7 +40,7 @@ export default class Authentication {
 
   async verifyCredentials() {
     const verifiedCredentials = await this.client.login(
-      this.connectionData.oauthVerifier
+      this.connectionData.oauthVerifier as string
     );
 
     return {
diff --git a/packages/backend/src/apps/typeform/authentication.ts b/packages/backend/src/apps/typeform/authentication.ts
index de563254..f644a55d 100644
--- a/packages/backend/src/apps/typeform/authentication.ts
+++ b/packages/backend/src/apps/typeform/authentication.ts
@@ -1,10 +1,13 @@
+import AuthenticationInterface from '../../types/interfaces/authentication-interface';
 import { URLSearchParams } from 'url';
 import axios, { AxiosInstance } from 'axios';
+import AppInfo from '../../types/app-info';
 import Field from '../../types/field';
+import JSONObject from '../../types/interfaces/json-object';
 
-export default class Authentication {
-  appData: any;
-  connectionData: any;
+export default class Authentication implements AuthenticationInterface {
+  appData: AppInfo;
+  connectionData: JSONObject;
   client: AxiosInstance = axios.create({
     baseURL: 'https://api.typeform.com',
   });
@@ -19,7 +22,7 @@ export default class Authentication {
     'workspaces:read',
   ];
 
-  constructor(appData: any, connectionData: any) {
+  constructor(appData: AppInfo, connectionData: JSONObject) {
     this.connectionData = connectionData;
     this.appData = appData;
   }
@@ -32,7 +35,7 @@ export default class Authentication {
 
   async createAuthData() {
     const searchParams = new URLSearchParams({
-      client_id: this.connectionData.consumerKey,
+      client_id: this.connectionData.consumerKey as string,
       redirect_uri: this.oauthRedirectUrl,
       scope: this.scope.join(' '),
     });
@@ -45,9 +48,9 @@ export default class Authentication {
   async verifyCredentials() {
     const params = new URLSearchParams({
       grant_type: 'authorization_code',
-      code: this.connectionData.oauthVerifier,
-      client_id: this.connectionData.consumerKey,
-      client_secret: this.connectionData.consumerSecret,
+      code: this.connectionData.oauthVerifier as string,
+      client_id: this.connectionData.consumerKey as string,
+      client_secret: this.connectionData.consumerSecret as string,
       redirect_uri: this.oauthRedirectUrl,
     });
 
diff --git a/packages/backend/src/types/interfaces/authentication-interface.ts b/packages/backend/src/types/interfaces/authentication-interface.ts
new file mode 100644
index 00000000..61c75f37
--- /dev/null
+++ b/packages/backend/src/types/interfaces/authentication-interface.ts
@@ -0,0 +1,10 @@
+import appInfoType from '../../types/app-info';
+import JSONObject from './json-object';
+
+export default interface AuthenticationInterface {
+  appData: appInfoType;
+  connectionData: JSONObject;
+  client: unknown;
+  verifyCredentials(): Promise<JSONObject>;
+  isStillVerified(): Promise<boolean>;
+}
diff --git a/packages/backend/src/types/interfaces/index.d.ts b/packages/backend/src/types/interfaces/index.d.ts
new file mode 100644
index 00000000..e13fa839
--- /dev/null
+++ b/packages/backend/src/types/interfaces/index.d.ts
@@ -0,0 +1 @@
+declare module 'interfaces';
diff --git a/packages/backend/src/types/interfaces/json-object.ts b/packages/backend/src/types/interfaces/json-object.ts
new file mode 100644
index 00000000..a051165f
--- /dev/null
+++ b/packages/backend/src/types/interfaces/json-object.ts
@@ -0,0 +1,9 @@
+type JSONValue = string | number | boolean | JSONObject | JSONArray;
+
+interface JSONObject {
+  [x: string]: JSONValue;
+}
+
+type JSONArray = Array<JSONValue>;
+
+export default JSONObject;
diff --git a/packages/backend/tsconfig.json b/packages/backend/tsconfig.json
index 0924afc8..158a30ba 100644
--- a/packages/backend/tsconfig.json
+++ b/packages/backend/tsconfig.json
@@ -9,18 +9,9 @@
     "outDir": "dist",
     "baseUrl": ".",
     "paths": {
-      "*": [
-        "node_modules/*",
-        "src/types/*"
-      ]
+      "*": ["node_modules/*", "src/types/*"]
     },
-    "typeRoots": [
-      "node_modules/@types",
-      "./src/types",
-      "./src/apps"
-    ]
+    "typeRoots": ["node_modules/@types", "./src/types", "./src/apps/*/types"]
   },
-  "include": [
-    "src/**/*"
-  ]
+  "include": ["src/**/*"]
 }