Chat App Development: How to Build a Chat App or Add In App Chat, With Features, Design, Architecture, Security and Cost

Updated October 2026 · Written and maintained by the Progression Agency strategy team

Chat app development is building the messaging layer of a product: one-to-one and group conversations, photos and files, delivery receipts, push notifications, moderation and the servers that deliver every message in order. Some teams build a standalone messenger; most add in app chat to a marketplace, service, community or support app. We design, build, launch and maintain iOS, Android and web apps, with a written scope before any code, and we build social, community and dating apps with messaging at their center. This guide covers chat app features, design, architecture, build or buy, security, app store rules, a build plan and chat app development cost.

What is chat app development?

Chat app development is the design and engineering of software that lets people exchange messages in real time, inside a standalone app or inside another product. It covers the screens people see and the systems behind them that store, order and deliver each message. The term is wide on purpose, so the first job in any chat app development project is to decide which kind of chat is being built.

How does a chat application work?

Developers summarize how chat application works in five parts. The client app on the phone lets a person write and send. A connection carries the message to a server. The server saves it in a message store and decides its place in the thread. It then delivers the message to each recipient’s device, and, if the app is closed, asks the phone’s push service to wake it. The flow chart below follows one message from the composer to the read receipt.

A standalone messenger, chat inside a product, or team chat?

A standalone messenger is the whole product, so it needs accounts, contacts, discovery and growth from nothing. Chat inside a product serves people who already have a reason to talk, such as a buyer and a seller, and it can lean on the app’s own accounts and rules. Team chat adds workplace needs: single sign-on, retention and admin controls. Each case needs different features and a different budget.

Chat app ideas that solve a business problem

The strongest chat app ideas answer a problem two parties already have. A buyer and a seller who must agree on details, a client and a provider who need to coordinate, the members of a paid community, field teams who need a shared thread, attendees at an event, or customers who need support. These are adult and business audiences, and in each the conversation has a clear purpose.

In app chat: adding chat to the app you already have

In app chat is a conversation between people that lives inside an app they already use. Many businesses that want chat do not need a new messenger; they need in app chat added to the product with the same accounts, rules and look. That choice shapes the whole build: an existing app already knows who its users are, and chat has to respect those relationships.

What is in-app chat, and how is it different from in-app messaging?

In-app chat is people talking to people. In-app messaging, as the term is often used, is the app talking to users: banners, prompts and announcements. The two share a name and nothing else, and they need different features, different risks and different rules. This guide is about the first. If you are reading about a tool that shows promotions inside your app, it belongs to the second.

In app chat functionality users expect on day one

People expect a conversation list with unread counts, push notifications when a message arrives, photos, and the ability to block and report. Without them chat feels unfinished, and the app stores will ask about the last two. Buying an in app chat SDK can supply many of these at once, and later sections compare that route with a build of your own.

Is chat in an app safe for users?

Chat in an app is as safe as the rules around it. Safety comes from reporting and blocking tools, rate limits that slow spammers, careful data handling and rules about who can contact whom. A marketplace may reveal contact details only after a booking. A community may let members message only people they have matched with. These choices belong in the scope, not in an afterthought.

Chat app features: what to build first

The chat app features worth building first are the ones people need to hold a conversation and to stay safe: one-to-one threads, attachments, delivery state, push and reporting. The table sorts the common features into first release and later, with the reason.

One-to-one and group conversations

A one-to-one thread has two members and a history. A group chat adds a list of members, roles such as owner and member, the ability to mute and to leave, and rules for who may add others. “Group chat” here names a feature; the design work lies in the membership rules, which change what the server must check on every send.

Photos, files, reactions, threads and search

Attachments need upload, storage, preview and a size limit. Reactions and threaded replies make busy conversations easier to follow. Search turns history into something useful, but it depends on how messages are stored, and it is hard to add if the store was built without it. Choose the attachments you need now and leave the rest of the list for later.

Delivery and read receipts, typing and presence

Each small signal is a message of its own. A typing indicator can fire many times a minute, and presence updates every time someone opens or closes the app. Receipts are valuable and cheap by comparison. Batching and throttling the noisy ones keeps the server from spending more on indicators than on the conversations themselves.

Voice and video calls: when to add them

Calls turn a chat product into a communications product, with its own testing, networks and costs. WebRTC, described at webrtc.org as an open web standard for real-time communication in browsers and on mobile, is the usual base. If your product needs voice chat app development, plan it as a second release. Our dating app development page shows chat and video built together for one kind of product.

Chat app design and messaging app design

Chat app design is the design of three screens people use all day: the inbox, the thread and the composer. Messaging app design adds the states in between: loading, empty, offline and failed. Good chat app UI design makes the next action obvious and the last message easy to find.

The inbox, the thread and the composer

The inbox lists conversations with the latest message, a timestamp and an unread count. The thread groups messages by day, shows who sent what and keeps the newest in view. The composer holds the text field, the attach button and the send control within thumb reach. Long press actions such as reply, copy and report sit behind a single gesture so the screen stays calm.

Notification, empty, offline and error states

Design the screens people see when things are not perfect. A new user with no conversations needs a clear first step. A phone with no signal needs to show that messages are waiting to send. A failed message needs a visible retry, not silence. These states are where a chat app most often disappoints people, so they deserve as much design as the main screens.

Accessible chat: screen readers, text size and contrast

WCAG 2.2, published by the W3C at w3.org, asks for a text contrast ratio of at least 4.5 to 1 for normal text and for text that can be resized up to 200 percent without losing content. A chat design that uses light gray timestamps or text that cannot be enlarged can fail both tests. This page makes no claim about the conformance of any app we build. For the design side see our UI and UX design page.

Chat app architecture: how a message reaches the other phone

Chat app architecture is the arrangement of connections, servers and stores that carries a message from one device to another and keeps it in order. The same ideas appear whether the team calls it real time chat architecture, messaging app system design or real time chat system design: an open connection, a durable store, fan out to recipients and push for closed apps.

Transport: WebSockets, MQTT or a managed service

The transport keeps a connection open so the server can send without being asked. The WebSocket protocol, RFC 6455, defines two-way communication between a browser application and a server, starting with an HTTP handshake. MQTT is an OASIS standard publish and subscribe protocol described as extremely lightweight. A managed service takes the problem away. Our social and community pages list “WebSockets or managed messaging”, which are the same choices.

Message store, ordering and delivery to every device

Every message needs a stable ID, a timestamp set by the server and a place in the thread. Sends should be safe to repeat, so a retry after a dropped connection does not create a duplicate. Delivery is per device, because one person may have a phone, a tablet and a browser open, and each must catch up on what it missed.

Push notifications through APNs and FCM

When the app is closed, push is the only way a message reaches the user. Apple’s notification documentation, at developer.apple.com, says push notifications keep people informed whether an app is running in the background or inactive, and the Firebase Cloud Messaging documentation describes a cross-platform messaging solution for Apple, Android and web clients. Apple’s guideline 4.5.4 adds that push must not be used for promotions unless people have opted in.

Offline sync and traffic spikes

Phones lose signal, so the app keeps a local cache and a retry queue that sends when the connection returns. Servers face the opposite problem: an event, a launch or a viral moment can bring everyone in at once. Backpressure, which means slowing intake rather than falling over, keeps the system alive during a surge.

Should you use a chat SDK or build your own messaging backend?

Use a hosted chat SDK when speed matters more than control, and build your own backend when data, moderation or cost at scale matter more. A chat SDK bundles the screens and the server logic; a chat API gives you the server logic only. Either way, the messaging API decision is the most expensive one to reverse.

What hosted chat SDKs and chat APIs provide

Stream describes its chat product as SDKs for React, Swift, Android, Flutter and React Native with moderation and offline support, per its own page at getstream.io. Sendbird describes a chat API and SDKs with real-time messaging infrastructure and a moderation dashboard, at sendbird.com. Twilio describes Conversations as APIs, or a self-hosted SDK, that keep conversation history across channels, at twilio.com. We name them only as examples of what such products say about themselves, with no partnership, reseller or certification of any kind.

When your own backend makes sense

Your own backend makes sense when messages must stay in a specific region or system, when moderation rules are unusual, when usage is high enough that per message fees outweigh engineering cost, or when chat is so tied to the product that a separate vendor gets in the way. It takes longer to start and needs people to run it, so the reasons should be concrete.

Questions to ask any chat vendor

Ask whether you can export all your data and in what format. Ask where it is stored and for how long. Ask how pricing is counted, and read the vendor’s pricing page on the day you decide, noting the date, because it can change. Ask what moderation tools exist, and how retention and deletion work for a user who leaves.

Chat app security: encryption in transit, at rest and end to end

Chat app security has three layers. Encryption in transit protects a message on the network, encryption at rest protects it where it is stored, and end to end encryption keeps it unreadable even to the service. Teams asking for a secure messaging app for business usually need the first two and a clear retention policy; the third has costs worth understanding first.

How does secure messaging work?

A secure messaging system encrypts the connection between the app and the server, usually with TLS, and encrypts stored data. In an end to end design the sender’s device encrypts so only the recipient’s device can read it. The public references are the Signal documentation at signal.org for two-party messaging and the Messaging Layer Security standard, RFC 9420, for group key establishment. We cite them as references; we make no claim to implement either.

What end-to-end encryption costs you: search, moderation and backups

An end to end encryption chat app cannot search message text on the server, cannot scan content for abuse there and cannot restore history from a server backup without extra design. Those are trade offs between privacy and features. Decide which side your product’s rules sit on before you pick the architecture.

Secure messaging for healthcare: where HIPAA applies

HIPAA applies when an app handles protected health information on behalf of a covered entity. The federal definition at 45 CFR 160.103 describes a business associate as a person who creates, receives, maintains or transmits protected health information on behalf of a covered entity. For a secure messaging app healthcare teams can rely on, the first question is whose data it is. A search for a HIPAA compliant messaging app is really a question about a whole system and its handling, not a feature. Read our healthcare app development and telemedicine app development pages.

Retention, export and deletion for business messaging

Business messaging needs retention rules, a way to hold records when required and a deletion path for a user who leaves. Apple says an app that supports account creation must let people initiate deletion within the app, per its account deletion page, and Google Play requires an in-app path and a web link. Chat history is part of what must be handled.

Moderation, safety and app store rules for chat apps

Both big app stores expect an app with user-generated content to let people report and block. A chat app is exactly that, so moderation is a requirement for approval, not an extra. The table lists what each store says.

What Apple requires of apps with user-generated content

Guideline 1.2 in Apple’s App Review Guidelines says such apps must include a method for filtering objectionable material, a mechanism to report offensive content with timely responses, the ability to block abusive users and published contact information. Build these in from the first release, and expect reviewers to test them.

Google Play’s user-generated content policy

The Google Play policy asks for robust and ongoing moderation, terms that users accept before posting, an in-app system for reporting and blocking, and action against content and users where appropriate. Apps with one-on-one interaction need user blocking.

Adults and businesses only: age gates and COPPA

This guide is not for apps aimed at children. The FTC’s COPPA FAQ says the rule covers services directed to children under 13 and general audience services with actual knowledge that they collect personal information from them. Keep your product adult and your age rules clear. Our social media app development and dating app development pages each cover safety for their own products.

How to build a chat app, step by step

How to build a chat app is mostly a question of order: agree the scope, build the conversation core, then add the pieces that make it reliable and safe. The timeline below shows the usual sequence. Anyone asking how to make a chat app or how to develop a chat app will meet the same stages.

Is it hard to build a chat app?

Sending a message is easy. Delivering it in order to every device, pushing it to a closed app, sending it again after a dropped connection and handling abuse is the hard part. A prototype is quick; a chat that survives real users takes a disciplined build. That gap is why this page treats how to build a messaging app as a product question, not a coding exercise. People also ask how to build a messenger app or how to build an instant messaging app; the order of work is the same.

Scope, platforms and the first release

We write a scope before any code, as our app pages state. For chat it names the user types, the contact rules, the platforms and the features for the first release, and it lists what waits. Choosing platforms early matters, because iPhone, Android and web each add testing.

Build a chat app in the right order

To build a chat app, start with accounts, then conversations, then the transport and the message store. Add push, then media. Add moderation and an admin console before launch, and analytics so you can see delivery. Teams who build a chat app in this order always have something working to test.

Testing on slow networks, old phones and busy evenings

Test with the network throttled, on the oldest phone you support and with many users sending at once. Kill the connection mid message and check that nothing is lost or duplicated. A chat that works on office wifi and fails on a train is not finished.

How to build a chat app like WhatsApp without copying it

How to build a chat app like WhatsApp is a question about features, not about the brand. A chat app like WhatsApp has accounts tied to a phone number, threads, group chats, media, receipts and calls. You can build that feature set; the name, icon, look and wording belong to WhatsApp and must not be copied.

What a WhatsApp clone app development scope includes

A WhatsApp clone app development scope lists phone number sign in, contacts, one-to-one and group threads, media, receipts, push, backups and calls, with a decision on each. We treat it as a scope example. The aim is a product with its own name, its own look and a reason to exist beyond being a copy.

What to leave out of version one

Leave out calls, status stories, channels and a desktop app until the core works. Each is a project in itself, and each can be added once people are talking. A first version that sends, delivers and moderates messages well is worth more than a long feature list.

How much does it cost to develop an app like WhatsApp?

The cost question, how much does it cost to develop a chat app, has no single answer. The cost depends on the feature set, the platforms and the volume. The cost section below gives labeled market bands for the main features, and our written scope turns your list into a quote.

Messaging app development by platform: iOS, Android, web and cross-platform

Messaging app development can target iPhone, Android, the browser or all three. The choice affects cost, speed and how native the result feels. Searches for messenger app development, instant messaging app development and Android chat app development all come down to which platforms to cover first.

Native iOS and Android chat apps

Native apps get the best access to the phone’s features, including push, background behavior and media. They cost more because there are two codebases. See our iOS app development company, Android app development company and native app development pages.

One codebase for both phones: React Native and Flutter chat builds

A single codebase serves both phones, and it fits most chat products. Heavy calling or unusual device features may still favor native code. Our pages cover React Native app development, Flutter app development and cross-platform app development.

Chat in the browser: web apps and PWAs

A web chat reaches people without an install, and a progressive web app can add home screen access. Browser limits on background work affect notifications. See our web app development company and progressive web app development pages.

Chat inside marketplaces, communities, dating, support and team apps

Most chat is added to another product, and each product shapes the rules. The question in every case is who may talk to whom, and what happens when something goes wrong.

Marketplace and on-demand apps

A buyer and a seller, or a client and a provider, need to agree details before they commit. Messages are the place for that, and masked contact details keep the transaction on the platform. See our on-demand app development and marketplace development pages.

Community, social and dating apps

Community products make chat central. Our social media app development page covers social and community products, and our dating app development page covers dating products.

Support chat, chatbots and handoff to a person

Support chat links a customer to an agent, and a chatbot may handle the first reply. This guide covers people talking to people. For automated replies see our AI chatbot development page.

Team chat and enterprise messaging

Team chat needs single sign-on, retention and admin controls for who can create channels and who can see what. See our enterprise app development page.

Chat app development cost

The cost depends on the features, the platforms, the user types and the compliance work, so our builds are quoted after a written scope. The table gives published US price bands for context, not for budgeting a quote.

How much does it cost to build a messaging app?

Our app builds are quoted after a written scope. The table shows published US market bands for the main pieces of a messaging product, taken from our app development cost guide. The feature rows are the added cost of a feature in a moderately complex app.

What moves the cost: user types, media, calls and compliance

The number of user types and rules, the amount of media, whether calls are included and how much compliance work the data needs move the cost most. A chat between two kinds of user is simpler than one with admins, moderators and members.

SDK fees, hosting and push after launch

After launch there are costs outside the build: hosting, storage, push and any chat SDK fees. Read each vendor’s own pricing page on the day you decide, and note the date, because prices change. Whatever the vendor charges is theirs, never ours.

How long chat app development takes

The schedule follows the scope: moderation, push and testing all take schedule. The pages for our social and dating work say a community app MVP commonly takes 4 to 6 months, and a dating MVP the same.

What sets the timeline

The user types, the platforms, whether calls are included and any compliance review set the timeline. Each added platform and each added feature adds testing as well as building.

What a first release can leave out

A first release can leave out reactions, threads, search, voice notes, calls and a desktop app. Keep what lets people talk safely: threads, delivery, push, block and report.

After launch: monitoring, abuse handling and retention

Launch is when real use starts, and chat needs watching. Monitoring shows whether messages arrive, and abuse handling shows whether people feel safe.

Delivery and latency numbers to watch

Track send success, time to deliver, push open rate and crash-free sessions. A rise in failed sends or slow delivery is usually the first sign of trouble.

Handling reports, blocks and bans

Reports need a queue, response targets that you set and an appeal path. A person must read the queue, and the targets should be ones the team can really meet.

Keeping people talking without spamming them

Push is how people return, and Apple’s guideline 4.5.4 requires explicit opt in for promotions. Ask for consent in clear language, offer an opt out and keep promotional push away from message alerts. For growth, see our app marketing agency page.

How AI assistants answer “who builds chat apps?”

AI assistants answer from the pages they can read. Google’s AI features documentation says a page can appear as a supporting link if it is indexed and eligible to be shown with a snippet, and that serving is not guaranteed.

What assistants read when a founder asks who builds chat apps

They read service pages, published scope and price wording, directories and reviews. Clear text, in plain words, gives an assistant something to quote. This describes what they draw on and promises nothing.

What a chat product should publish so assistants describe it correctly

Publish what the product does, who it is for, what it costs and how to reach you, in text. Our AEO for SaaS page goes further.

Choosing a chat app development company

The company you pick should be able to explain how it would deliver a message, not only show screens. The same goes for a messaging app development company or a team of chat app developers.

Questions for chat app developers before you sign

Ask which transport they would pick and why, how they test delivery, what the moderation plan is, whether you can export your data and who owns the code and the accounts.

Why we write the scope before the code

We write a scope before any code, as our app pages state. It fixes what the first release holds, so a quote can be compared. See our MVP development and hire app developers pages.

Get a free proposal for your chat app

Send us the product, the user types and the platforms. We reply with a free proposal and a written scope.

Related services for chat apps

These pages cover the apps, platforms and skills around a chat product.

• Social media app development
• Dating app development
• Telecom software development
• Healthcare app development
• Telemedicine app development
• Mental health app development
• AI chatbot development
• AI agent development
• App development cost
• React Native app development
• Flutter app development
• Cross-platform app development
• Native app development
• iOS app development company
• Android app development company
• Web app development company
• Progressive web app development
• Enterprise app development
• SaaS development
• MVP development
• Hire app developers
• App development outsourcing
• Backend development
• API development
• Cloud app development
• UI and UX design
• On-demand app development
• Marketplace development
• Event app development
• Salon app development
• App marketing agency
• AEO for SaaS
• HIPAA compliant software development

Frequently asked questions