How to Build an AI Email Responder App with Flutter and Back4App

introduction in this tutorial, you will build an ai powered email responder app using flutter for the frontend and back4app for the backend the app will integrate with email services like gmail or outlook, analyze incoming emails using ai models (such as openai's gpt 3), and generate personalized responses by the end of this tutorial, you will have a functional app that can manage emails, generate automated responses, and allow users to personalize their email interactions this app leverages the power of back4app's parse server to handle user authentication, data storage, and cloud functions, providing a scalable backend solution without the need to manage server infrastructure integrating ai capabilities and email services will enhance your flutter development skills and provide a foundation for building advanced, data driven applications prerequisites to complete this tutorial, you will need a back4app account sign up for a free account at back4app https //www back4app com/ flutter sdk installed on your local machine follow the official flutter installation guide https //flutter dev/docs/get started/install for your operating system basic knowledge of dart and flutter development if you're new to flutter, consider reviewing the flutter documentation https //flutter dev/docs before proceeding familiarity with rest apis and asynchronous programming in dart an account with an ai service provider (e g , openai) sign up for an api key to access ai models an email account (gmail or outlook) for integration testing step 1 — setting up your back4app backend in this step, you will create a new back4app application, set up your data classes, and configure the backend to work with your flutter app 1 1 create a new application on back4app log in to your back4app dashboard https //dashboard back4app com/ click on "create new app" enter an app name (e g , "ai email responder") and select your app icon choose your server location if prompted click "create" 1 2 retrieve application keys in your app's dashboard, navigate to app settings > security & keys note down the application id and client key you will need these for your flutter app configuration 1 3 define your data model classes we will create the following classes in back4app user (default) emailaccount emailtemplate responsehistory 1 3 1 create the emailaccount class go to database > browser click "create a class" choose "custom" and name it emailaccount click "create class" add the following columns to emailaccount user (pointer< user>) points to the user object emailaddress (string) accounttype (string) e g , gmail, outlook authtoken (string) will store encrypted tokens 1 3 2 create the emailtemplate class repeat the steps to create a new class named emailtemplate add the following columns to emailtemplate user (pointer< user>) templatename (string) templatecontent (string) templatetype (string) e g , formal, casual, follow up 1 3 3 create the responsehistory class create a new class named responsehistory add the following columns to responsehistory user (pointer< user>) originalemailsummary (string) generatedresponse (string) usereditedresponse (string) timesaved (number) 1 4 set class level permissions ensure that only authenticated users can access their data in each class, go to the security section set class level permissions (clp) to allow read/write access only to authenticated users step 2 — initializing your flutter project in this step, you will set up your flutter project and configure it to connect to back4app 2 1 create a new flutter project open your terminal and run flutter create ai email responder navigate to the project directory cd ai email responder 2 2 add required dependencies open pubspec yaml and add the following dependencies dependencies flutter sdk flutter parse server sdk flutter ^4 0 1 flutter email sender ^5 0 2 http ^0 13 4 provider ^6 0 2 fl chart ^0 45 1 run flutter pub get to install the packages 2 3 initialize parse in your app create a new file lib/config/back4app config dart // lib/config/back4app config dart const string keyapplicationid = 'your application id'; const string keyclientkey = 'your client key'; const string keyparseserverurl = 'https //parseapi back4app com'; replace 'your application id' and 'your client key' with the keys from back4app in lib/main dart , initialize parse // lib/main dart import 'package\ flutter/material dart'; import 'package\ parse server sdk flutter/parse server sdk dart'; import 'config/back4app config dart'; import 'app dart'; void main() async { widgetsflutterbinding ensureinitialized(); await parse() initialize( keyapplicationid, keyparseserverurl, clientkey keyclientkey, autosendsessionid true, debug true, ); runapp(myapp()); } create lib/app dart // lib/app dart import 'package\ flutter/material dart'; import 'screens/home screen dart'; class myapp extends statelesswidget { @override widget build(buildcontext context) { return materialapp( title 'ai email responder', theme themedata( primaryswatch colors blue, ), home homescreen(), ); } } step 3 — implementing user authentication you will now implement user registration and login using parse server 3 1 create authentication screens create lib/screens/login screen dart and lib/screens/signup screen dart for brevity, we'll focus on the login functionality // lib/screens/login screen dart import 'package\ flutter/material dart'; import 'package\ parse server sdk flutter/parse server sdk dart'; import 'home screen dart'; class loginscreen extends statefulwidget { @override loginscreenstate createstate() => loginscreenstate(); } class loginscreenstate extends state\<loginscreen> { final texteditingcontroller usernamecontroller = texteditingcontroller(); final texteditingcontroller passwordcontroller = texteditingcontroller(); future\<void> douserlogin() async { final username = usernamecontroller text trim(); final password = passwordcontroller text trim(); final user = parseuser(username, password, null); final response = await user login(); if (response success) { navigator pushreplacement( context, materialpageroute(builder (context) => homescreen()), ); } else { showerror(response error! message); } } void showerror(string message) { scaffoldmessenger of(context) showsnackbar(snackbar(content text('error $message'))); } @override widget build(buildcontext context) { return scaffold( appbar appbar( title text('login'), ), body padding( padding const edgeinsets all(16), child column( children \[ textfield( controller usernamecontroller, decoration inputdecoration(labeltext 'username', icon icon(icons person)), ), textfield( controller passwordcontroller, decoration inputdecoration(labeltext 'password', icon icon(icons lock)), obscuretext true, ), sizedbox(height 20), elevatedbutton( onpressed douserlogin, child text('login'), ), ], ), ), ); } } 3 2 update home screen navigation modify lib/app dart to direct users to the login screen if they are not authenticated // lib/app dart import 'package\ flutter/material dart'; import 'package\ parse server sdk flutter/parse server sdk dart'; import 'screens/home screen dart'; import 'screens/login screen dart'; class myapp extends statelesswidget { future\<bool> hasuserloggedin() async { final currentuser = await parseuser currentuser() as parseuser?; return currentuser != null; } @override widget build(buildcontext context) { return futurebuilder\<bool>( future hasuserloggedin(), builder (context, snapshot) { if (snapshot hasdata && snapshot data == true) { return materialapp( title 'ai email responder', theme themedata(primaryswatch colors blue), home homescreen(), ); } else { return materialapp( title 'ai email responder', theme themedata(primaryswatch colors blue), home loginscreen(), ); } }, ); } } step 4 — integrating email services in this step, you will set up the email integration using the flutter email sender package 4 1 configure email sender add necessary permissions to your android and ios configurations for android , update android/app/src/main/androidmanifest xml \<uses permission android\ name="android permission internet"/> for ios , ensure that your info plist includes \<key>nsapptransportsecurity\</key> \<dict> \<key>nsallowsarbitraryloads\</key> \<true/> \</dict> 4 2 implement email sending functionality create lib/services/email service dart // lib/services/email service dart import 'package\ flutter email sender/flutter email sender dart'; class emailservice { future\<void> sendemail(string subject, string body, list\<string> recipients) async { final email email = email( body body, subject subject, recipients recipients, ishtml false, ); await flutteremailsender send(email); } } 4 3 implement email fetching (placeholder) email fetching from providers like gmail requires oauth and api integration, which can be complex for this tutorial, we will simulate email fetching create lib/models/email dart // lib/models/email dart class email { final string sender; final string subject; final string body; final datetime date; email({ required this sender, required this subject, required this body, required this date, }); } create lib/services/email service dart (update with dummy data) // lib/services/email service dart import ' /models/email dart'; class emailservice { future\<list\<email>> fetchemails() async { // simulate network delay await future delayed(duration(seconds 2)); return \[ email( sender 'john doe\@example com', subject 'meeting reminder', body 'don\\'t forget about our meeting tomorrow at 10 am ', date datetime now() subtract(duration(hours 1)), ), // add more dummy emails ]; } // existing sendemail method } step 5 — integrating ai services for response generation you will now set up the ai integration to generate email responses 5 1 set up http requests to ai api install the http package (already added) create lib/services/ai service dart // lib/services/ai service dart import 'dart\ convert'; import 'package\ http/http dart' as http; class aiservice { final string apikey = 'your openai api key'; final string apiurl = 'https //api openai com/v1/engines/davinci/completions'; future\<string> generateresponse(string emailcontent) async { final response = await http post( uri parse(apiurl), headers { 'authorization' 'bearer $apikey', 'content type' 'application/json', }, body jsonencode({ 'prompt' 'reply to the following email \n$emailcontent', 'max tokens' 150, }), ); if (response statuscode == 200) { final data = jsondecode(response body); return data\['choices']\[0]\['text'] trim(); } else { throw exception('failed to generate response'); } } } note replace 'your openai api key' with your actual api key 5 2 implement the response editor widget create lib/widgets/response editor dart // lib/widgets/response editor dart import 'package\ flutter/material dart'; class responseeditor extends statelesswidget { final string initialresponse; final texteditingcontroller controller; responseeditor({required this initialresponse}) controller = texteditingcontroller(text initialresponse); @override widget build(buildcontext context) { return textfield( controller controller, maxlines null, decoration inputdecoration( hinttext 'edit your response here ', border outlineinputborder(), ), ); } } 5 3 displaying ai generated responses in lib/screens/email detail screen dart , integrate the ai service // lib/screens/email detail screen dart import 'package\ flutter/material dart'; import ' /models/email dart'; import ' /services/ai service dart'; import ' /widgets/response editor dart'; import ' /services/email service dart'; class emaildetailscreen extends statefulwidget { final email email; emaildetailscreen({required this email}); @override emaildetailscreenstate createstate() => emaildetailscreenstate(); } class emaildetailscreenstate extends state\<emaildetailscreen> { final aiservice aiservice = aiservice(); final emailservice emailservice = emailservice(); string? airesponse; bool isloading = false; future\<void> generateresponse() async { setstate(() { isloading = true; }); try { final response = await aiservice generateresponse(widget email body); setstate(() { airesponse = response; }); } catch (e) { scaffoldmessenger of(context) showsnackbar(snackbar(content text('ai error $e'))); } finally { setstate(() { isloading = false; }); } } void sendresponse(string responsetext) { emailservice sendemail( 're ${widget email subject}', responsetext, \[widget email sender], ); scaffoldmessenger of(context) showsnackbar(snackbar(content text('email sent'))); } @override void initstate() { super initstate(); generateresponse(); } @override widget build(buildcontext context) { final responseeditor = airesponse != null ? responseeditor(initialresponse airesponse!) null; return scaffold( appbar appbar( title text('email from ${widget email sender}'), ), body padding( padding const edgeinsets all(16), child isloading ? center(child circularprogressindicator()) column( children \[ text(widget email body), sizedbox(height 20), responseeditor != null ? expanded(child responseeditor) container(), elevatedbutton( onpressed () { if (responseeditor != null) { sendresponse(responseeditor controller text); } }, child text('send response'), ), ], ), ), ); } } step 6 — managing email templates you will now implement email template management using back4app 6 1 define the emailtemplate model create lib/models/email template dart // lib/models/email template dart import 'package\ parse server sdk flutter/parse server sdk dart'; class emailtemplate extends parseobject implements parsecloneable { emailtemplate() super('emailtemplate'); emailtemplate clone() this(); @override emailtemplate clone(map\<string, dynamic> map) => emailtemplate clone() fromjson(map); string? get templatename => get\<string>('templatename'); set templatename(string? value) => set\<string>('templatename', value); string? get templatecontent => get\<string>('templatecontent'); set templatecontent(string? value) => set\<string>('templatecontent', value); string? get templatetype => get\<string>('templatetype'); set templatetype(string? value) => set\<string>('templatetype', value); } 6 2 implement template service create lib/services/template service dart // lib/services/template service dart import 'package\ parse server sdk flutter/parse server sdk dart'; import ' /models/email template dart'; class templateservice { future\<list\<emailtemplate>> fetchtemplates() async { final query = querybuilder\<emailtemplate>(emailtemplate()); final response = await query find(); if (response success && response results != null) { return response results as list\<emailtemplate>; } else { return \[]; } } future\<void> addtemplate(emailtemplate template) async { await template save(); } } 6 3 create template management screen create lib/screens/template management screen dart // lib/screens/template management screen dart import 'package\ flutter/material dart'; import ' /models/email template dart'; import ' /services/template service dart'; class templatemanagementscreen extends statefulwidget { @override templatemanagementscreenstate createstate() => templatemanagementscreenstate(); } class templatemanagementscreenstate extends state\<templatemanagementscreen> { final templateservice templateservice = templateservice(); list\<emailtemplate> templates = \[]; bool isloading = true; future\<void> loadtemplates() async { final fetchedtemplates = await templateservice fetchtemplates(); setstate(() { templates = fetchedtemplates; isloading = false; }); } @override void initstate() { super initstate(); loadtemplates(); } @override widget build(buildcontext context) { return scaffold( appbar appbar( title text('email templates'), ), body isloading ? center(child circularprogressindicator()) listview\ builder( itemcount templates length, itembuilder (context, index) { final template = templates\[index]; return listtile( title text(template templatename ?? 'unnamed'), subtitle text(template templatetype ?? 'no type'), ); }, ), floatingactionbutton floatingactionbutton( onpressed () { // implement template creation }, child icon(icons add), )); } } step 7 — implementing response history tracking you will now save the ai generated responses and user edits to back4app for analytics 7 1 define the responsehistory model create lib/models/response history dart // lib/models/response history dart import 'package\ parse server sdk flutter/parse server sdk dart'; class responsehistory extends parseobject implements parsecloneable { responsehistory() super('responsehistory'); responsehistory clone() this(); @override responsehistory clone(map\<string, dynamic> map) => responsehistory clone() fromjson(map); string? get originalemailsummary => get\<string>('originalemailsummary'); set originalemailsummary(string? value) => set\<string>('originalemailsummary', value); string? get generatedresponse => get\<string>('generatedresponse'); set generatedresponse(string? value) => set\<string>('generatedresponse', value); string? get usereditedresponse => get\<string>('usereditedresponse'); set usereditedresponse(string? value) => set\<string>('usereditedresponse', value); int? get timesaved => get\<int>('timesaved'); set timesaved(int? value) => set\<int>('timesaved', value); } 7 2 save response history after sending email update lib/screens/email detail screen dart in the sendresponse method import ' /models/response history dart'; // void sendresponse(string responsetext) async { await emailservice sendemail( 're ${widget email subject}', responsetext, \[widget email sender], ); // save response history final responsehistory = responsehistory() set('originalemailsummary', widget email body) set('generatedresponse', airesponse) set('usereditedresponse', responsetext) set('timesaved', calculatetimesaved()); await responsehistory save(); scaffoldmessenger of(context) showsnackbar(snackbar(content text('email sent'))); navigator pop(context); } int calculatetimesaved() { // placeholder implementation return 5; // assume 5 minutes saved } step 8 — adding analytics with charts you will now implement a basic analytics dashboard using fl chart 8 1 implement analytics service create lib/services/analytics service dart // lib/services/analytics service dart import 'package\ parse server sdk flutter/parse server sdk dart'; import ' /models/response history dart'; class analyticsservice { future\<list\<responsehistory>> fetchresponsehistories() async { final query = querybuilder\<responsehistory>(responsehistory()); final response = await query find(); if (response success && response results != null) { return response results as list\<responsehistory>; } else { return \[]; } } future\<int> calculatetotaltimesaved() async { final histories = await fetchresponsehistories(); return histories fold(0, (sum, item) => sum + (item timesaved ?? 0)); } } 8 2 create analytics dashboard create lib/screens/analytics screen dart // lib/screens/analytics screen dart import 'package\ flutter/material dart'; import 'package\ fl chart/fl chart dart'; import ' /services/analytics service dart'; class analyticsscreen extends statefulwidget { @override analyticsscreenstate createstate() => analyticsscreenstate(); } class analyticsscreenstate extends state\<analyticsscreen> { final analyticsservice analyticsservice = analyticsservice(); int totaltimesaved = 0; future\<void> loadanalytics() async { final timesaved = await analyticsservice calculatetotaltimesaved(); setstate(() { totaltimesaved = timesaved; }); } @override void initstate() { super initstate(); loadanalytics(); } @override widget build(buildcontext context) { return scaffold( appbar appbar( title text('analytics'), ), body center( child text('total time saved $totaltimesaved minutes'), )); } } step 9 — implementing offline support you will now add offline capabilities to your app using parse's local data store 9 1 enable local data store in lib/main dart , enable the local datastore await parse() initialize( keyapplicationid, keyparseserverurl, clientkey keyclientkey, autosendsessionid true, debug true, corestore await corestoresembastimp getinstance(), ); 9 2 modify data models for pinning in your models (e g , responsehistory ), add methods to pin and unpin objects future\<void> pin() async { await this pin(); } future\<void> unpin() async { await this unpin(); } 9 3 implement offline manager create lib/utils/offline manager dart // lib/utils/offline manager dart import ' /models/email dart'; import 'package\ parse server sdk flutter/parse server sdk dart'; class offlinemanager { future\<void> cacheemails(list\<email> emails) async { for (var email in emails) { final parseobject = parseobject('email') set('sender', email sender) set('subject', email subject) set('body', email body) set('date', email date); await parseobject pin(); } } future\<list\<email>> getcachedemails() async { final query = querybuilder\<parseobject>(parseobject('email')); final response = await query frompin() find(); if (response success && response results != null) { return response results! map((e) { return email( sender e get\<string>('sender') ?? '', subject e get\<string>('subject') ?? '', body e get\<string>('body') ?? '', date e get\<datetime>('date') ?? datetime now(), ); }) tolist(); } else { return \[]; } } } 9 4 use offline data when no connectivity in your email fetching logic, check for connectivity and use cached data if offline conclusion in this tutorial, you built an ai email responder app using flutter and back4app you set up a back4app backend with necessary data models and security configurations initialized a flutter project and connected it to back4app implemented user authentication with parse server integrated email sending and simulated email fetching integrated ai services to generate email responses managed email templates and stored them in back4app tracked response history for analytics added basic analytics using fl chart implemented offline support using parse's local data store this app provides a foundation for building more advanced features, such as real email integration with oauth, advanced ai capabilities, and improved ui/ux design next steps email integration implement real email fetching using gmail or outlook apis with oauth authentication enhanced ai features fine tune ai prompts for better responses and implement personalization based on user data ui/ux improvements enhance the app's interface for better user experience testing and deployment write unit and integration tests and prepare the app for deployment to app stores security enhancements encrypt sensitive data and implement robust error handling and input validation for more information on using back4app with flutter, refer to the back4app flutter guide https //www back4app com/docs/flutter/parse sdk/