Authentication System for Your Social Network

introduction in this tutorial, you will learn how to implement a comprehensive authentication system for your social network web application using back4app as your backend service you'll build functionality for user registration, login, password reset, and session management critical features for any modern social application back4app is a backend as a service (baas) platform built on parse server that allows developers to create scalable applications without managing server infrastructure its built in user authentication capabilities make it perfect for quickly implementing secure user management systems by the end of this tutorial, you'll have created a fully functional authentication system similar to the one used in back4gram, a social network application you'll implement user registration with validation, secure login, password recovery, and persistent sessions across the application, giving your users a seamless experience while keeping their accounts secure back4gram project find here the complete code for a social network sample project built with back4app prerequisites to complete this tutorial, you will need a back4app account you can sign up for a free account at back4app com https //www back4app com a back4app project set up you can learn how to create a new project by following our getting started with back4app guide https //www back4app com/docs/get started/welcome node js installed on your local machine basic knowledge of javascript, react js, and restful api concepts familiarity with modern web development concepts (components, state management, etc ) step 1 – understanding back4app's user management system before diving into code, it's important to understand how back4app handles user management back4app is built on parse server, which provides a special parse user class designed specifically for authentication the parse user class the parse user class in back4app extends the standard parse object with specialized functionality for user authentication it includes several built in fields username a unique identifier for the user (required) password the user's password (required for signup but not stored in retrievable form) email the user's email address (optional but recommended) emailverified a boolean indicating whether the user has verified their email authdata authentication data for third party authentication you can also add custom fields to store additional user information, such as profile pictures, bios, or any other user specific data session management when a user logs in, back4app creates a session token that identifies the user's session this token is used to authenticate subsequent requests without requiring the user to log in again the session token is automatically managed by the parse sdk but can also be manually controlled if needed here's how the session flow works user provides credentials (username/email and password) back4app validates the credentials if valid, back4app creates a session token the token is stored locally (typically in localstorage or a similar mechanism) the token is included in subsequent api requests to authenticate the user let's look at how this is implemented in the back4gram application the parse initialization code typically looks like this // initialize parse with your back4app credentials parse initialize("your app id", "your javascript key"); parse serverurl = "https //parseapi back4app com/"; this setup in the back4gram app allows all components to access the parse sdk and make authenticated requests once a user logs in security features back4app provides several security features for user management secure password storage passwords are never stored in plain text but are hashed and salted automatically session management user sessions can be managed and revoked through the back4app dashboard access control lists (acls) you can control who can read or write specific objects email verification back4app can send verification emails to users password reset built in functionality for secure password resets now that we understand the basics, let's move on to setting up our project back4gram project find here the complete code for a social network sample project built with back4app step 2 – setting up your project to demonstrate how to implement authentication with back4app, we'll create a simplified version of the back4gram social network application creating a new react application first, let's create a new react application open your terminal and run npx create react app social network auth cd social network auth installing required packages next, we'll install the necessary packages npm install parse react router dom @chakra ui/react @emotion/react @emotion/styled framer motion these packages provide parse the javascript sdk for back4app react router dom for page routing @chakra ui/react a component library for building the ui project structure let's set up a basic file structure for our authentication system src/ ├── components/ │ └── ui/ │ ├── field js │ └── toaster js ├── pages/ │ ├── signuppage js │ ├── loginpage js │ ├── resetpasswordpage js │ ├── profilepage js │ └── feedpage js ├── app js └── index js configuring parse sdk now, let's initialize parse in our application create a file called src/parseconfig js import parse from 'parse/dist/parse min js'; // initialize parse parse initialize("your app id", "your javascript key"); parse serverurl = "https //parseapi back4app com/"; export default parse; replace your app id and your javascript key with your back4app project credentials you can find these in your back4app dashboard under app settings > security & keys next, let's update src/index js to import our parse configuration import react from 'react'; import reactdom from 'react dom/client'; import ' /index css'; import app from ' /app'; import ' /parseconfig'; const root = reactdom createroot(document getelementbyid('root')); root render( \<react strictmode> \<app /> \</react strictmode> ); setting up routes now, let's set up the basic routing structure in src/app js import react from 'react'; import { browserrouter as router, routes, route } from 'react router dom'; import {provider} from " /components/ui/provider"; // import pages import signuppage from ' /pages/signuppage'; import loginpage from ' /pages/loginpage'; import resetpasswordpage from ' /pages/resetpasswordpage'; import profilepage from ' /pages/profilepage'; import feedpage from ' /pages/feedpage'; function app() { return ( \<provider> \<router> \<routes> \<route path="/signup" element={\<signuppage />} /> \<route path="/login" element={\<loginpage />} /> \<route path="/reset password" element={\<resetpasswordpage />} /> \<route path="/profile" element={\<profilepage />} /> \<route path="/feed" element={\<feedpage />} /> \<route path="/" element={\<loginpage />} /> \</routes> \</router> \</provider> ); } export default app; creating ui components before we start building the authentication pages, let's create some reusable ui components first, let's create src/components/ui/toaster js // a simple toast notification system export const toaster = { create ({ title, description, type }) => { alert(`${title} ${description}`); // in a real app, you would use chakra ui's toast system } }; then, create src/components/ui/field js import react from 'react'; import { formcontrol, formlabel, formerrormessage, formhelpertext } from '@chakra ui/react'; export const field = ({ label, children, errortext, helpertext, rest }) => { return ( \<formcontrol isinvalid={!!errortext} { rest}> {label && \<formlabel>{label}\</formlabel>} {children} {errortext ? ( \<formerrormessage>{errortext}\</formerrormessage> ) helpertext ? ( \<formhelpertext>{helpertext}\</formhelpertext> ) null} \</formcontrol> ); }; now we're ready to implement our authentication system! back4gram project find here the complete code for a social network sample project built with back4app step 3 – creating a user registration system let's start by implementing the signup page this page will allow new users to create an account by providing a username, email, and password create a file called src/pages/signuppage js import react, { usestate } from 'react'; import { usenavigate, link as routerlink } from 'react router dom'; import { box, button, heading, input, vstack, link, text, flex } from '@chakra ui/react'; import parse from 'parse/dist/parse min js'; import { toaster } from ' /components/ui/toaster'; import { field } from ' /components/ui/field'; function signuppage() { const \[username, setusername] = usestate(''); const \[email, setemail] = usestate(''); const \[password, setpassword] = usestate(''); const \[confirmpassword, setconfirmpassword] = usestate(''); const \[isloading, setisloading] = usestate(false); const \[showpassword, setshowpassword] = usestate(false); const \[errors, seterrors] = usestate({}); const navigate = usenavigate(); const validateform = () => { const newerrors = {}; if (!username trim()) { newerrors username = 'username is required'; } if (!email trim()) { newerrors email = 'email is required'; } else if (!/\s+@\s+\\ \s+/ test(email)) { newerrors email = 'email is invalid'; } if (!password) { newerrors password = 'password is required'; } else if (password length < 6) { newerrors password = 'password must be at least 6 characters'; } if (password !== confirmpassword) { newerrors confirmpassword = 'passwords do not match'; } seterrors(newerrors); return object keys(newerrors) length === 0; }; const handlesignup = async (e) => { e preventdefault(); if (!validateform()) { return; } setisloading(true); try { // create a new user using parse const user = new parse user(); user set('username', username); user set('email', email); user set('password', password); await user signup(); toaster create({ title 'success', description 'account created successfully!', type 'success', }); navigate('/feed'); } catch (error) { console error('error signing up ', error); toaster create({ title 'error', description error message, type 'error', }); } finally { setisloading(false); } }; return ( \<box maxw="400px" mx="auto" p={4}> \<vstack spacing={6} align="stretch"> \<heading textalign="center">create an account\</heading> \<form onsubmit={handlesignup}> \<vstack spacing={4} align="stretch"> \<field isinvalid={!!errors username}> \<field label>username\</field label> \<input type="text" value={username} onchange={(e) => setusername(e target value)} /> {errors username && ( \<field errortext>{errors username}\</field errortext> )} \</field> \<field isinvalid={!!errors email}> \<field label>email\</field label> \<input type="email" value={email} onchange={(e) => setemail(e target value)} /> {errors email && ( \<field errortext>{errors email}\</field errortext> )} \</field> \<field isinvalid={!!errors password}> \<field label>password\</field label> \<flex position="relative"> \<input type={showpassword ? 'text' 'password'} value={password} onchange={(e) => setpassword(e target value)} /> \<button aria label={showpassword ? 'hide password' 'show password'} size="xs" position="absolute" right="0 25rem" top="50%" transform="translatey( 50%)" onclick={() => setshowpassword(!showpassword)} zindex={2} \> {showpassword ? 'hide' 'show'} \</button> \</flex> {errors password && ( \<field errortext>{errors password}\</field errortext> )} \</field> \<field isinvalid={!!errors confirmpassword}> \<field label>confirm password\</field label> \<input type={showpassword ? 'text' 'password'} value={confirmpassword} onchange={(e) => setconfirmpassword(e target value)} /> {errors confirmpassword && ( \<field errortext>{errors confirmpassword}\</field errortext> )} \</field> \<button type="submit" colorscheme="blue" isloading={isloading} mt={2} \> sign up \</button> \</vstack> \</form> \<text textalign="center"> already have an account?{' '} \<link as={routerlink} to="/login" color="blue 400"> log in \</link> \</text> \</vstack> \</box> ); } export default signuppage; this code creates a signup form with the following features form validation checks that all required fields are filled out correctly before submission password visibility toggle allows users to see what they're typing error handling displays appropriate error messages for validation and signup failures loading state shows a loading indicator during the signup process understanding back4app's user signup process the key part of this code is the handlesignup function, which uses back4app's parse user class to create a new user const user = new parse user(); user set('username', username); user set('email', email); user set('password', password); await user signup(); when you call signup() , back4app validates the provided data securely hashes the password creates a new user in the database creates and returns a session token the session token is automatically stored by the parse sdk after a successful signup, the user is automatically logged in, so we can redirect them directly to the feed page in the back4gram application, this is implemented in a similar way in signuppage js the main difference is that the back4gram implementation uses more advanced ui components and might include additional fields or validation logic with the signup functionality complete, let's move on to implementing the login functionality back4gram project find here the complete code for a social network sample project built with back4app step 4 – implementing user login now, let's create the login page that will allow users to authenticate with their credentials create a file called src/pages/loginpage js import react, { usestate, useeffect } from 'react'; import { usenavigate, link as routerlink } from 'react router dom'; import { box, heading, input, button, text, vstack, link, } from '@chakra ui/react'; import parse from 'parse/dist/parse min js'; import { toaster } from ' /components/ui/toaster'; import { field } from ' /components/ui/field'; function loginpage() { const \[username, setusername] = usestate(''); const \[password, setpassword] = usestate(''); const \[isloading, setisloading] = usestate(false); const \[error, seterror] = usestate(''); const \[currentuser, setcurrentuser] = usestate(null); const navigate = usenavigate(); // check if a user is already logged in useeffect(() => { const checkcurrentuser = async () => { try { const user = await parse user current(); if (user) { setcurrentuser(user); navigate('/feed'); } } catch (error) { console error('error checking current user ', error); } }; checkcurrentuser(); }, \[navigate]); const handlelogin = async (e) => { e preventdefault(); if (!username || !password) { seterror('username and password are required'); return; } setisloading(true); try { // login with parse const loggedinuser = await parse user login(username, password); toaster create({ title 'login successful!', description `welcome back, ${loggedinuser getusername()}!`, type 'success', }); // redirect to feed after successful login navigate('/feed'); } catch (error) { toaster create({ title 'login failed', description error message, type 'error', }); seterror(error message); } finally { setisloading(false); } }; return ( \<box maxw="md" mx="auto" p={8} border="1px solid" bordercolor="gray 600" borderradius="md"> \<heading as="h1" size="xl" mb={6} textalign="center"> social network login \</heading> \<form onsubmit={handlelogin}> \<vstack spacing={4}> \<field label="username"> \<input type="text" value={username} onchange={(e) => setusername(e target value)} placeholder="your username" required /> \</field> \<field label="password" errortext={error} \> \<input type="password" value={password} onchange={(e) => setpassword(e target value)} placeholder="your password" required /> \</field> \<link as={routerlink} to="/reset password" alignself="flex end" fontsize="sm"> forgot password? \</link> \<button colorscheme="blue" width="full" type="submit" isloading={isloading} \> log in \</button> \</vstack> \</form> \<text textalign="center" mt={6}> don't have an account?{' '} \<link as={routerlink} to="/signup" color="blue 500"> sign up \</link> \</text> \</box> ); } export default loginpage; this login page has the following features auto redirect if a user is already logged in, they're automatically redirected to the feed page form validation ensures that username and password are provided before submission error handling displays appropriate error messages for failed login attempts loading state shows a loading indicator during the login process password reset link provides a link to the password reset page understanding back4app's login process the key parts of this code are checking for an existing logged in user using parse user current() logging in a user with parse user login(username, password) when a user logs in with back4app the credentials are sent to the server for validation if valid, a session token is generated and returned the parse sdk automatically stores this token the user object is returned with the current user's data the stored session token is then used automatically by the parse sdk for all subsequent requests, allowing the user to stay logged in in the back4gram application, the login system is implemented similarly in loginpage js , but with more advanced ui components and potentially additional features like social login options now let's move on to implementing the password reset functionality back4gram project find here the complete code for a social network sample project built with back4app step 5 – password reset functionality next, let's create the password reset page that will allow users to recover their accounts if they forget their passwords create a file called src/pages/resetpasswordpage js import react, { usestate } from 'react'; import { link as routerlink } from 'react router dom'; import { box, heading, input, button, text, vstack, link, alert, alerticon, alerttitle, alertdescription, } from '@chakra ui/react'; import parse from 'parse/dist/parse min js'; import { toaster } from ' /components/ui/toaster'; import { field } from ' /components/ui/field'; function resetpasswordpage() { const \[email, setemail] = usestate(''); const \[isloading, setisloading] = usestate(false); const \[error, seterror] = usestate(''); const \[issuccess, setissuccess] = usestate(false); const handleresetpassword = async (e) => { e preventdefault(); if (!email) { seterror('email is required'); return; } // basic email validation const emailregex = /^\[^\s@]+@\[^\s@]+\\ \[^\s@]+$/; if (!emailregex test(email)) { seterror('invalid email format'); return; } setisloading(true); seterror(''); try { // request password reset await parse user requestpasswordreset(email); setissuccess(true); toaster create({ title 'email sent', description 'check your inbox for password reset instructions ', type 'success', }); } catch (error) { toaster create({ title 'reset request failed', description error message, type 'error', }); seterror(error message); } finally { setisloading(false); } }; return ( \<box maxw="md" mx="auto" p={8} border="1px solid" bordercolor="gray 600" borderradius="md"> \<heading as="h1" size="xl" mb={6} textalign="center"> reset password \</heading> {issuccess ? ( \<alert status="success" borderradius="md"> \<alerticon /> \<box> \<alerttitle>email sent successfully!\</alerttitle> \<alertdescription> check your inbox for password reset instructions \</alertdescription> \</box> \</alert> ) ( \<form onsubmit={handleresetpassword}> \<vstack spacing={4}> \<text> enter your email and we'll send you instructions to reset your password \</text> \<field label="email" errortext={error} \> \<input type="email" value={email} onchange={(e) => setemail(e target value)} placeholder="your email address" required /> \</field> \<button colorscheme="blue" width="full" type="submit" isloading={isloading} \> send instructions \</button> \<link as={routerlink} to="/login" color="blue 500"> back to login \</link> \</vstack> \</form> )} \</box> ); } export default resetpasswordpage; this password reset page includes email validation ensures that a valid email format is provided success state shows a success message after the reset email is sent error handling displays appropriate error messages if the reset request fails loading state shows a loading indicator during the reset request process understanding back4app's password reset process the key part of this code is using back4app's parse user requestpasswordreset(email) method to send a password reset email to the user when a user requests a password reset with back4app back4app verifies that the email exists in the database if the email is found, a reset email is sent to the user the email contains a link with a secure token when the user clicks the link, they're directed to a password reset page after setting a new password, they can log in with their new credentials in the back4gram application, the password reset functionality is implemented similarly in resetpasswordpage js , using the same back4app api methods but potentially with more advanced ui components or additional features now that we've implemented the core authentication features, let's focus on session management back4gram project find here the complete code for a social network sample project built with back4app step 6 – session management and persistence one of the key aspects of any authentication system is proper session management this ensures that users stay logged in while navigating through your application and that their sessions are secure let's create a simplified version of the feed page to demonstrate session checking and management create a file called src/pages/feedpage js import react, { usestate, useeffect } from 'react'; import { usenavigate } from 'react router dom'; import { box, heading, button, text, vstack, hstack, spinner, center, } from '@chakra ui/react'; import parse from 'parse/dist/parse min js'; import { toaster } from ' /components/ui/toaster'; function feedpage() { const \[isloading, setisloading] = usestate(true); const \[currentuser, setcurrentuser] = usestate(null); const navigate = usenavigate(); // check if user is authenticated useeffect(() => { const checkauth = async () => { try { console log('checking authentication '); const user = await parse user current(); if (!user) { console log('no user found, redirecting to login'); navigate('/login'); return; } console log('user authenticated ', user id, user get('username')); setcurrentuser(user); setisloading(false); } catch (error) { console error('error checking authentication ', error); navigate('/login'); } }; checkauth(); }, \[navigate]); // function to handle logout const handlelogout = async () => { try { await parse user logout(); navigate('/login'); } catch (error) { console error('error logging out ', error); toaster create({ title 'error', description 'failed to log out please try again ', type 'error', }); } }; if (isloading) { return ( \<center h="100vh"> \<spinner size="xl" /> \</center> ); } return ( \<box maxw="800px" mx="auto" p={8}> \<hstack justify="space between" mb={8}> \<heading>social network feed\</heading> \<hstack> \<text>welcome, {currentuser get('username')}\</text> \<button onclick={handlelogout} colorscheme="red" variant="outline"> log out \</button> \</hstack> \</hstack> \<vstack align="stretch" spacing={4}> \<box p={4} borderwidth={1} borderradius="md"> \<text>this is your feed when authenticated with back4app, you'll see content here \</text> \<text mt={2}>your user id {currentuser id}\</text> \<text>your email {currentuser get('email')}\</text> \</box> \</vstack> \</box> ); } export default feedpage; this feed page implements authentication check verifies that the user is logged in before showing content automatic redirect redirects to the login page if no user session is found logout functionality allows the user to log out and clear their session user information display shows information about the currently logged in user understanding back4app's session management back4app handles sessions in several ways automatic session storage the parse sdk automatically stores the session token after login current user access you can access the current user with parse user current() session expiration sessions typically expire after a set period (configurable in back4app) logout you can end a session with parse user logout() in a production application like back4gram, session management is often more complex in the messagespage js file of back4gram, we can see how authentication is checked at the beginning of the component useeffect(() => { const checkauth = async () => { try { console log('checking authentication '); const user = await parse user current(); if (!user) { console log('no user found, redirecting to login'); navigate('/login'); return; } console log('user authenticated ', user id, user get('username')); setcurrentuser(user); fetchconversations(user); } catch (error) { console error('error checking authentication ', error); navigate('/login'); } }; checkauth(); // clean up subscriptions when component unmounts // }, \[navigate]); this pattern of checking for authentication at the component level is common in react applications using back4app session security considerations when implementing session management with back4app, consider these security practices automatic session invalidation configure back4app to invalidate sessions after a certain period of inactivity secure storage ensure session tokens are stored securely (the parse sdk handles this automatically) https only always use https to prevent session token interception logout on sensitive actions require re authentication for sensitive operations like changing passwords let's now look at how to implement profile management to complete our authentication system back4gram project find here the complete code for a social network sample project built with back4app step 7 – adding user profile management the final piece of our authentication system is user profile management this allows users to view and update their profile information create a file called src/pages/profilepage js import react, { usestate, useeffect } from 'react'; import { usenavigate } from 'react router dom'; import { box, button, heading, text, vstack, hstack, input, textarea, avatar, formcontrol, formlabel, spinner, center, } from '@chakra ui/react'; import parse from 'parse/dist/parse min js'; import { toaster } from ' /components/ui/toaster'; import { field } from ' /components/ui/field'; function profilepage() { const \[user, setuser] = usestate(null); const \[username, setusername] = usestate(''); const \[email, setemail] = usestate(''); const \[bio, setbio] = usestate(''); const \[isloading, setisloading] = usestate(true); const \[isupdating, setisupdating] = usestate(false); const \[selectedfile, setselectedfile] = usestate(null); const \[avatarurl, setavatarurl] = usestate(null); const navigate = usenavigate(); // fetch user data useeffect(() => { const fetchuserdata = async () => { try { const currentuser = await parse user current(); if (!currentuser) { navigate('/login'); return; } setuser(currentuser); setusername(currentuser get('username') || ''); setemail(currentuser get('email') || ''); setbio(currentuser get('bio') || ''); // get avatar if available const avatar = currentuser get('avatar'); if (avatar) { setavatarurl(avatar url()); } setisloading(false); } catch (error) { console error('error fetching user data ', error); toaster create({ title 'error', description 'failed to load profile data', type 'error', }); navigate('/login'); } }; fetchuserdata(); }, \[navigate]); // handle profile update const handleupdateprofile = async (e) => { e preventdefault(); setisupdating(true); try { if (!user) return; user set('username', username); user set('email', email); user set('bio', bio); // handle avatar upload if a file is selected if (selectedfile) { const parsefile = new parse file(selectedfile name, selectedfile); await parsefile save(); user set('avatar', parsefile); setavatarurl(parsefile url()); } await user save(); toaster create({ title 'success', description 'profile updated successfully', type 'success', }); } catch (error) { console error('error updating profile ', error); toaster create({ title 'error', description error message, type 'error', }); } finally { setisupdating(false); } }; // handle avatar selection const handlefilechange = (e) => { if (e target files && e target files\[0]) { setselectedfile(e target files\[0]); // create a preview url const previewurl = url createobjecturl(e target files\[0]); setavatarurl(previewurl); } }; // handle logout const handlelogout = async () => { try { await parse user logout(); navigate('/login'); } catch (error) { console error('error logging out ', error); } }; if (isloading) { return ( \<center h="100vh"> \<spinner size="xl" /> \</center> ); } return ( \<box maxw="800px" mx="auto" p={8}> \<hstack justify="space between" mb={8}> \<heading>your profile\</heading> \<button onclick={handlelogout} colorscheme="red" variant="outline"> log out \</button> \</hstack> \<box p={8} borderwidth={1} borderradius="md"> \<form onsubmit={handleupdateprofile}> \<vstack spacing={6} align="start"> \<hstack spacing={8} w="full" align="start"> \<vstack align="center" minw="150px"> \<avatar size="2xl" src={avatarurl} name={username} mb={4} /> \<formcontrol> \<formlabel htmlfor="avatar upload" cursor="pointer" textalign="center"> \<button as="span" size="sm"> change avatar \</button> \<input id="avatar upload" type="file" accept="image/ " onchange={handlefilechange} display="none" /> \</formlabel> \</formcontrol> \</vstack> \<vstack spacing={4} flex="1"> \<field label="username" w="full"> \<input value={username} onchange={(e) => setusername(e target value)} /> \</field> \<field label="email" w="full"> \<input type="email" value={email} onchange={(e) => setemail(e target value)} /> \</field> \<field label="bio" w="full"> \<textarea value={bio} onchange={(e) => setbio(e target value)} placeholder="tell us about yourself" rows={4} /> \</field> \</vstack> \</hstack> \<button type="submit" colorscheme="blue" isloading={isupdating} alignself="flex end" \> save changes \</button> \</vstack> \</form> \</box> \</box> ); } export default profilepage; this profile page provides users with the ability to 1\ view profile information see their username, email, and bio 2\ update profile details change their username, email, and bio 3\ upload a profile picture select and upload a profile image 4\ log out end their session and return to the login page \### understanding back4app's user data management let's examine the key aspects of how back4app handles user data management \#### file uploads with parse file one powerful feature of back4app is the ability to easily handle file uploads using `parse file` ```javascript if (selectedfile) { const parsefile = new parse file(selectedfile name, selectedfile); await parsefile save(); user set('avatar', parsefile); setavatarurl(parsefile url()); } when you create a new parse file , back4app takes your file (image, document, etc ) uploads it to secure storage returns a reference that can be stored with your user object makes the file accessible via a url adding custom user fields back4app's parse user class can be extended with custom fields beyond the default ones in our example, we've added bio a text field for user descriptions avatar a file field for profile pictures you can add any custom fields you need for your application's user profiles user set('bio', bio); in the back4gram application, the profilepage js implements similar functionality but with more features and a more complex ui it includes additional fields like follower counts, post statistics, and more robust image handling back4gram project find here the complete code for a social network sample project built with back4app step 8 – testing and securing your authentication system now that we've built our authentication system, let's discuss how to properly test and secure it testing authentication flows when testing your authentication system, you should verify each of these flows user registration test that users can create accounts with valid credentials input validation verify that appropriate errors appear for invalid inputs login process ensure users can login with correct credentials failed login check that appropriate errors appear for incorrect credentials password reset confirm the password reset flow works end to end session persistence verify that users remain logged in between page visits logout process ensure users can properly logout and sessions are terminated common security vulnerabilities to avoid when building authentication systems, be aware of these common security issues password storage never store passwords in plain text back4app handles this for you automatically brute force attacks implement rate limiting for login attempts back4app provides this functionality cross site scripting (xss) sanitize user inputs to prevent script injection cross site request forgery (csrf) use proper tokens to verify request authenticity insecure direct object references don't expose sensitive ids or references in urls back4app security best practices back4app provides several security features you should leverage 1\ class level permissions (clps) in your back4app dashboard, you can set class level permissions to control who can read, write, and delete objects go to your back4app dashboard navigate to database → browser click on the "security" button for your user class configure permissions appropriately \[image back4app class level permissions screen showing user class security settings] for user class, typical settings include public read access only for specific fields (username, avatar) no public write or delete access only authenticated users can update their own records 2\ access control lists (acls) for individual objects, you can use acls to control access // set an acl that only allows the current user to read and write this object const useracl = new parse acl(parse user current()); userobject setacl(useracl); await userobject save(); this ensures that only the user who created an object can access or modify it 3\ master key usage back4app provides a master key that bypasses security checks never expose this in client side code // never do this in client side code parse cloud usemasterkey(); // this should only be used in cloud code instead, for operations that require elevated privileges, use cloud functions 4\ email verification enable email verification in your back4app settings to ensure users provide valid email addresses go to your back4app dashboard navigate to app settings → email settings configure your email adapter enable email verification \[image back4app email settings configuration screen] 5\ two factor authentication for additional security, you can implement two factor authentication using back4app cloud functions this requires users to provide a second form of verification (typically a code sent to their phone or email) when logging in implementing rate limiting to protect against brute force attacks, you can implement rate limiting using cloud functions // cloud function to handle login with rate limiting parse cloud define("securelogin", async (request) => { const { username, password } = request params; // check for too many failed attempts const query = new parse query("loginattempt"); query equalto("username", username); query greaterthan("createdat", new date(date now() 15 60 1000)); // last 15 minutes const attempts = await query count(); if (attempts >= 5) { throw new error("too many login attempts please try again later "); } try { // attempt to log in const user = await parse user login(username, password); return { success true, user user tojson() }; } catch (error) { // record failed attempt const loginattempt = parse object extend("loginattempt"); const attempt = new loginattempt(); attempt set("username", username); await attempt save(null, { usemasterkey true }); throw error; } }); conclusion in this tutorial, you've built a comprehensive authentication system for a social network application using back4app you've implemented user registration, login, password reset, and profile management features, all powered by back4app's built in user management capabilities let's recap what you've learned back4app's user management system you've learned how back4app's parse server provides built in user authentication with the parse user class user registration you've implemented a signup form that creates new user accounts in back4app's database user login you've created a login system that authenticates users and manages sessions password reset you've added a secure password reset feature that sends recovery emails session management you've learned how to maintain user sessions and protect routes profile management you've built a profile page that allows users to update their information and upload profile pictures security best practices you've explored how to secure your authentication system using back4app's security features with back4app, you were able to focus on creating a great user experience rather than building complex backend infrastructure the parse server that powers back4app provided all the necessary authentication apis, while also ensuring your user data remains secure the authentication system you've built forms the foundation of your social network application with this in place, you can now expand your application by adding features like posts, comments, likes, and direct messaging, all using back4app as your backend service next steps social login integration add login with google, facebook, or other providers using back4app's oauth capabilities enhanced security implement two factor authentication for additional security user roles set up role based access control for different types of users real time features add real time messaging and notifications using back4app's live query for the complete code of the back4gram social network application, you can check out the github repository https //github com/templates back4app/back4gram back4app's powerful backend services and parse server integration make it an excellent choice for building secure, scalable social network applications by leveraging its built in user management capabilities, you can create a robust authentication system with minimal effort, allowing you to focus on creating unique features that make your application stand out