Design Your Own Communication App

Since the introduction of first-gen consumer messaging apps like AIM in the 1990s, chat has solidified its role as a mainstream method of communication. In many situations, users choose chat or instant messaging apps over other ways of contacting each other. Chat's asynchronous nature eliminates the urgency and pressure of a phone call, but it still feels faster, more immediate, and less formal than email.

The market for consumer chat applications is dominated by a handful of major players, but constantly evolving technologies and consumer needs create opportunities for new chat and messaging applications to gain market share. Not every new chat app has to go head to head with WhatsApp, either — opportunities abound for specialized messaging applications that serve specific groups of users or support communication across industries as diverse as gaming, dating, and healthcare.

Once a product team or a startup founder has identified an opportunity to build a chat app, research into the best chat development processes can quickly return an overwhelming volume of information. Hundreds if not thousands of code examples are available online for chat app projects of all types and sizes, but it can be difficult to determine whether a given approach will meet your needs without a great deal of time-consuming and costly trial and error. Another decision product teams face early on is whether to build or buy chat functionality. Development costs can be unpredictable, and it's challenging to strike the right balance between a unique, customized chat product and one that feels familiar and intuitive while performing reliably.

If you're in the process of planning and scoping a chat app project and/or gathering and allocating resources for that project, this comprehensive guide is for you. As a leading provider of chat technology, we've distilled everything you need to know into a digestible overview, from competitive analysis to chat features, technical requirements, development steps, and common challenges. For a holistic look at every ingredient that goes into building a commercially successful messaging app, read the entire guide straight through — or, if you're short on time, skip to the most relevant sections using the table of contents below.

Contents

Competitive Analysis: Leading Chat App Examples
Time & Cost to Build a Chat App
Chat App Features to Build
Technical Considerations: Frameworks, Tools, & Expertise
Chat App Development Steps: Process Overview
Chat App Development Challenges to Anticipate
Final Thoughts: Choosing a Chat Technology Provider

Note: This guide doesn't provide line-by-line coding instructions, in part because there are so many different ways to code a chat app depending on your use case, experience level, and specific requirements. If you're a software engineer ready to dive into your chat build, choose the technical guide that's right for you from our library of more than 100 chat development tutorials.

Competitive Analysis: Leading Chat App Examples

Chat app competition is fierce. Most new messaging apps fail to achieve widespread adoption, unable to combine reliable performance at scale with the engaging, addictive user experience it takes to make an app go viral. Teams preparing to launch a new product into a market this crowded need a comprehensive understanding of their competitors' strengths and weaknesses before they begin to map out feature priorities, make technical decisions, or allocate engineering resources. Careful examination of what the following top chat apps do right — and where they fall short — should produce valuable insight to inform your own chat app build.

Considered by many to be the gold standard for peer-to-peer messaging applications, WhatsApp rose to ubiquity in the 2010s as an alternative to SMS messaging. By transmitting messages using the internet instead of cellular data, WhatsApp helps users avoid data overages. WhatsApp was also among the first mainstream mobile chat apps to offer end-to-end encryption (E2EE), securing messages so that they can't be read by anyone other than the sender and receiver — not even by WhatsApp. The combination of free internet transmission and E2EE makes WhatsApp extremely popular for chatting with friends and family in different countries.

Though WhatsApp built its reputation around secure messaging, its 2014 acquisition by Facebook has led some users to question the app's integrity when it comes to protecting their personal data and message content. In search of more privacy and peace of mind, these users are turning to lesser-known secure messaging apps like Signal and Telegram. Whether or not accusations about WhatsApp compromising its values are true, the shift in user perception creates an opportunity for competitors looking to take a chunk of this giant's market share.

WhatsApp uses the Extensible Messaging and Presence Protocol (XMPP), one of the oldest and most widely adopted frameworks for instant messaging over the internet. It's worth brushing up on how XMPP works as part of your research to decide which frameworks will power your own chat application.

For a technical breakdown of how to emulate the features and functions that make WhatsApp so popular, check out our code tutorial with step-by-step instructions to build a WhatsApp clone on Android with Kotlin.

Key WhatsApp Features at a Glance:

Cross-platform support for Android, iOS, Mac, Windows, and web
End-to-end encryption (E2EE)
Groups (channels) for up to 256 users with customizable notifications
Text, photo, video, and audio messages
Voice and video calls over the internet
Photo sharing from device storage or direct using built-in camera app
File sharing for PDFs, documents, spreadsheets, slideshows, etc., up to 100MB
Support for Venmo-like payments in some countries

iMessage

Apple's built-in chat app adds significant value to its range of device offerings, and iMessage's familiarity and flexibility make it the default for most iPhone users. The ability to seamlessly switch between messaging over the internet vs SMS means users can text each other from practically anywhere without having to think about whether WiFi, cellular data, or SMS makes the most sense at that moment. The iMessage UI is clean and intuitive to use, with functionality designed to make the most of the smartphone touchscreen experience instead of merely adapting to it. Users drag messages to the left to see timestamps, for example, press and hold a message to access reactions, and drag a conversation to the left to mute or delete it.

With continuous investment, Apple manages to keep iMessage both familiar and fresh at the same time. Users discover new features playfully, sometimes by accident and sometimes when they see their friends start to use them, while the core blue-and-white message bubbles stay reassuringly consistent. This ability to balance the old with the new — not to mention the fact that it comes pre-installed on Apple devices — makes iMessage a particularly tough competitor for those looking to make their own chat app. Still, close examination reveals a handful of opportunities for others to compete.

One of the most obvious ways to one-up iMessage is to support Android and Windows devices, ensuring a consistent experience for all users regardless of their participation in the Apple device ecosystem. To this day, the experience of exchanging messages between Android and iOS is cringeworthy at best, and iPhone users who own Windows PCs or Chromebooks don't get to enjoy the benefits of iMessage's cross-device syncing. Another opportunity for improvement, at least as of February 2021, could be a cleaner, more intuitive message threading feature — we're glad Apple finally added threads, but we're hearing that a lot of users find the current version cumbersome to use and overwhelming to look at.

Key iMessage Features at a Glance:

Cross-device syncing between iOS on iPhone, iPad, and Apple Watch, and macOS on desktop
Typing indicators
Group messages
SMS support
Optional read receipts
Reactions
Threads
Audio messages
Talk-to-text
Easy photo sharing from camera roll or directly from integrated camera app
App integrations with Apple Pay, Stickers, Apple Music, and other popular apps

Slack

Thanks to Slack, the concept of team chat has revolutionized the way knowledge workers collaborate. More spontaneous and more flexible than email, Slack lets colleagues touch base on projects, share jokes and memes, and everything in between. Slack's inherent fun factor helped propel the app to ubiquity in the 2010s, and the app played a critical role in supporting the 2020's massive shift to remote work.

In a number of ways, the team chat use case presents more complex development problems compared to simpler one-on-one messaging apps. Those looking to build a Slack clone will need to support the topic-oriented channel format made popular by Slack, along with individual direct messaging and ad-hoc group messaging. The app will also need to be architected for multi-tenancy, keeping each customer's chat environment walled off from the others.

A world-class team chat experience like Slack also requires a number of advanced features that other apps can do without. These include deep integrations with popular apps like Google Calendar, Google Drive, and, of course, Giphy, along with slash commands and the ability to use Slack as a conversational interface to control other apps. Mentions (who doesn't love a good @here?), reactions, emojis, and nice clean conversation threads all work together to give Slack users a polished, professional experience.

Key Slack Features at a Glance:

Cross-platform support for Android, iOS, web, and desktop
Group messaging, channels, and direct messaging
Support for numerous external app integrations
Slash commands
Conversation threads
Reactions
Mentions
File attachments
Audio and video calling
Slackbot conversational AI
Automated reminders
Pinned messages
Saved messages

Facebook Messenger & Instagram Messenger

Once upon a time, Facebook Messenger was a simple and wildly popular in-app chat feature inseparable from the earlier web-only versions of Facebook.com. But Facebook's deliberate effort to separate Facebook Messenger, which launched as a standalone app in 2011, created a more powerful and dynamic platform that now competes with other leaders in the field. The transition to the standalone Messenger app was completed in 2014, when the social media giant forced users to either download Messenger or give up in-app chat altogether. Like other changes from Facebook, the change initially upset some users, but most have since come around to accept it.

Facebook Messenger's expanded adoption has not for the most part come from building the most advanced, feature-rich app. Instead, Facebook has used its popularity to influence when, how, and why people turn to Facebook Messenger, expanding intended use cases beyond casual chatting with friends. Examples of expanded use cases include messaging with sellers on Facebook Marketplace, messaging with local businesses for sales and customer service inquiries, and now, the ability to centralize Instagram and Facebook DMs in a single app.

Messenger benefits from Facebook's dominance over the social media world — it's familiar, it's easy to use, and it's just there, deeply integrated with Facebook and automatically synced with your Facebook friends list. But on the flipside, that means Messenger isn't immune to Facebook's pitfalls. As users and governments around the world continue to scrutinize Facebook's privacy policies, its treatment of user data, and its shifting role in disseminating knowledge and information, opportunities may arise for chat app competitors who offer a similarly delightful product with less baggage and fewer strings attached.

Key Facebook Messenger Features at a Glance

"Rooms" for group video calls
Customizable reactions using any emoji
AR effects, message effects, and selfie stickers
Users can choose custom UI themes and colors
Integrations with Facebook, WhatsApp, Instagram, and Portal
Optional push notifications
Threaded replies
Optional device fingerprint authentication
Support for payments via credit card or PayPal (US only)
Sales and customer support chat with businesses
Ability to message friends on Instagram from Messenger
Optional two-factor authentication (2FA) and end-to-end encryption (E2EE)

Time & Cost to Build a Chat App

The time and cost required to build a chat app can vary greatly — an accurate estimate will need to account for variables like the size of your team and its members' areas of expertise, your app's goals and desired feature set, scaling and infrastructure costs, and post-launch maintenance and improvement work. We'll cover the basics here, and you can find a more comprehensive breakdown of how to estimate chat build cost in our article weighing the classic build vs. buy dilemma.

All it takes is a little subconscious bias to arrive at an overly optimistic estimate of the total build cost. Then, a couple of months into the project, you realize it's going way over budget — and on top of that, you're going to have to compromise on some of the originally planned functionality, at least for now. To prevent this scenario, plan for the unplanned and make sure you're not missing any hidden costs in your initial estimate. Not everything is going to go perfectly the first time — bugs, scaling issues, and other surprises are part of software development, and they should be part of your cost estimate, too.

With the above variables in mind, the basic methodology for your cost calculation should be consistent. The following formula can serve as a reference point to avoid overlooking any hidden cost factors:

Simplified Chat Build Cost
=
Initial Build Cost [Developer Salaries + Infrastructure Over Expected Finite Time Period]
+
Maintenance & Scaling Cost [Initial Break-Fix & Customer Feedback Period as Usage Grows + Recurring Infrastructure Costs]

Most skilled engineering teams should be able to launch an MVP chat app in around three months, and a very rough estimate puts the initial cost around $50,000 - $100,000. Factors like cross-platform development, advanced feature requirements, and scalability (all discussed below) can quickly multiply the project's time and cost.

Chat App Features to Build

The best messaging apps provide a cohesive experience so simple and intuitive that end users don't necessarily notice individual features. Where other types of apps use multiple pages and navigation menus, great chat apps usually just open a keyboard below a message window, so each feature feels like an intrinsic part of the whole.

This presents an interesting problem for developers and product teams working to reverse-engineer and replicate a successful chat app: It's easy to be overconfident, rush the research stage, and start coding without accounting for all of the individual components that will be required. You don't want to be a couple of sprints into your chat build and then realize you didn't include an easy way to integrate some important feature down the road.

The following list of chat app features should serve as a solid reference point to help avoid mistakes and isolate individual components that will need attention. The list is divided into two sections, with universal, mission-critical features first, followed by advanced features that can enhance the user experience and help tailor your chat app to its intended audience and use case.

Core Features for Every Chat App

Regardless of the intended use case, the following chat features will be necessary to support any basic messaging experience.

App registration page and user authentication mechanism
Message text editing field with keyboard
Conversation window with sent and received messages clearly distinguished from each other and ordered chronologically
List of contacts with easy contact import and editing functionality
Ability to package and send a message
Ability to receive, interpret, and display a message
Notifications, unread message counts, and/or message states (read/unread)
Storage of past messages
User presence indication (available, away, offline, time last active)

Advanced Features for a Competitive Chat Experience

Although it's possible to launch an MVP with only the basic features above, the truth is that today's users expect more. Leading chat apps continue to innovate, adding features that make it easier, faster, and more fun to send and receive messages. Take iMessage reactions, which Apple calls "Tapbacks," for example. Though some users found Tapbacks confusing and ambiguous when they launched in 2016, they've by now been absorbed into messaging culture as an efficient way to acknowledge the kind of message that doesn't call for a long-winded response.

The following advanced chat features can help your app stand out, creating a polished experience that boosts engagement and retention. Note that depending on your audience and use case, some of these features may not just be nice to have, but necessary.

Message reactions let users choose a quick response without typing
Thread replies visually group chat messages with replies on the same topic
AI text and image moderation keeps conversations clean when message volume or other factors make human moderation difficult
URL enrichment shows image, text, and video previews of URLs users send
@mentions make sure the right people see important messages that might otherwise get buried in a group chat
Push notifications let users receive updates when they're not actively checking the app
Flexible permissions allow for admins, moderators, and other user roles needed in some chat use cases
Slash commands let users interact with integrated external apps via their APIs
Media attachments let users share files and view some file types without leaving your app
Silent messages let special messages send without marking a channel as unread
Typing indicators keep users engaged while waiting for a reply
Read receipts decrease uncertainty and provide situational context in between messages
Delivery receipts provide peace of mind for users on unreliable connections
Public channels let users form and join communities large and small
Private channels let users associate with only chosen group members
CDN storage reduces latency in long-distance communication
Webhooks let your app send notification texts and emails to offline users and allow for chatbot integrations
Language translation connects users across continents and cultures
SAML single sign-on (SSO) and multi-factor authentication (MFA) increase authentication security and convenience
Multi-tenant and team functionality separates unaffiliated groups of users from each other
View more advanced chat features

Now that you've mapped out your use case and feature requirements, you have some decisions to make in terms of how to approach your chat build. You'll need to choose the frameworks, protocols, infrastructure, and front-end and back-end coding languages that match your team's goals and expertise. The right tools and frameworks can make certain tasks easier, with common problems solved using pre-built objects instead of requiring lower-level code. Additional research may be required, but here's an overview of some of the most popular languages, protocols, and tools that can be used to build a chat app.

For a more technical window into the types of decisions you'll make, read our post on why Stream Chat switched from Python to Go.

Chat App Code Languages

Consider the pros and cons of each language, your existing skill set, and your requirements for features, platform support, and scalability when selecting which language(s) you'll work with.

Back-End Language Options

Go
- Pros: Extremely fast and extremely scalable.
- Cons: Steep learning curve; probably requires at least one dedicated dev hire.
Python
- Pros: Great for machine learning (ML) and data science.
- Cons: Relatively slow and doesn't scale well.
Java
- Pros: Long-lived popular language with an abundance of Java developer talent.
- Cons: Is aging and becoming thought of as a legacy language.
C#
- Pros: Used for native Windows apps, has been updated and kept modern, popular with enterprise applications due to historic Microsoft prevalence there.
- Cons: Aging, mostly used for legacy apps, though more updated than Java.
Scala
- Pros: Highly scalable, super threaded. Used by Twitter.
- Cons: Relatively obscure.
PHP
- Pros: Widely known language that supports WordPress; can be a good choice for web development.
- Cons: Relatively slow and not very scalable; not the most efficient language.
Ruby
- Pros: Relatively low-level language popular with new devs of the coding bootcamp generation.
- Cons: Not as well-known in the broader dev community.
JavaScript (front-end and back-end)
- Pros: Node.js back-end framework is easy to learn for devs with front-end JavaScript experience.
- Cons: Optimization based on lightweight front-end JavaScript tasks can make CPU-bound back-end Node.js tasks cumbersome.

Suitable Front-End Languages for Chat

React (JavaScript)
- Easy setup, cost-effective, open source UI layer based on JavaScript libraries
- Overall a solid front-end language for many chat apps, especially web versions
React Native (JavaScript)
- Larger framework for building cross-platform apps
- Overall a solid front-end language for many chat apps, especially mobile versions using the same codebase on multiple platforms (ie Android and iOS)
Flutter
- Intuitive cross-platform framework, relatively approachable to learn, fast development, easy and extensive UI customization
Swift (iOS)
- Best for providing a truly native, familiar UX on Apple mobile devices; automatic support for Dynamic Type, Dark Mode, localization, and accessibility
- Only for iOS; cross-platform development will require additional investment
Kotlin or Java (Android)
- Best for providing a truly native, familiar UX on Android mobile devices
- Android-specific; cross-platform development will require additional investment

Popular Chat App Frameworks

Beyond coding languages themselves, a number of protocols and frameworks have been developed specifically to support chat functionality and reduce the manual labor required to build that functionality. You'll want to familiarize yourself with the following technologies and make informed decisions about which to integrate with your build.

Chat App Protocols

If you're building chat from scratch, you'll also need to decide which back-end protocol you'll rely on to transmit messages. One popular open-source option is the Extensible Messaging and Presence Protocol (XMPP), which powers WhatsApp and has a rich community of developers sharing support and sample projects. Others prefer the newer Message Queue Telemetry Transport (MQTT) protocol over XMPP, in part because it doesn't require messages to be formatted as XML documents. WebRTC is a promising newer protocol that supports voice, video, and generic data transmission between peers. Though WebRTC can be fairly complicated to learn, it's becoming popular as a component in services designed to support high-quality multimedia streaming and video calls, such as dolby.io.

Message Markup Language (MML)

Message Markup Language (MML) is another library to consider integrating into your chat app build. MML makes it easier to support a dynamic messaging experience, with the ability to embed components like button lists, carousel interfaces, date pickers/appointment schedulers, and custom forms within your chat experience. MML also supports images, icons, and tables out of the box. It's a standardized way to handle the most common use cases for message interactivity, a feature that more and more users expect now that major players like iMessage support it.

Chat App Development Tools

With the right developer tools, you don't have to start your chat app build from scratch. Consider the three options below with your requirements for cost, performance, and scalability in mind.

Firebase

Google's multi-purpose app development tool can seem like an obvious go-to for building chat, but it does have a few drawbacks. Firebase can help you build just about anything quickly, but it's not necessarily optimized for chat — its pricing structure quickly becomes impractical when your user base begins to scale. Firebase also has a maximum limit of 100,000 concurrent connections, which could force a future migration if adoption goes well. And, compared to a chat-specific framework, building with Firebase means building from scratch, which can be costly in terms of developer time. With these challenges in mind, many dev teams working on large-scale commercial apps turn to chat-specific Firebase alternatives.

WebSockets & Socket.io

WebSockets and Socket.io make up another popular approach to building real-time communication functionality like chat. Socket.io provides a browser-based JavaScript client library that connects to a Node.js server over the WebSocket protocol. Although Socket.io provides the real-time portion of chat, it doesn't scale well with an influx of users — it requires a lot of memory in the form of a lot of extra servers, and those costs can add up quickly. Additionally, Socket.io does not offer additional features out of the box, such as data persistence. As with Firebase, Socket.io can be an interesting tool to tinker with, but when it comes to developing a scalable commercial chat app, better purpose-built options exist.

Chat Messaging APIs & SDKs

Researching, evaluating, and choosing the right technical components to build a chat app can be overwhelming. Almost no one can be an expert in all of the above technologies, so it's hard to know for sure which approach is best for your needs. Instead of working through each of these decisions from scratch, many of today's engineering and product teams prefer to build on top of a dedicated chat API and SDK solution. With this type of solution, the vendor takes responsibility for providing reliable, scalable, feature-rich chat functionality, freeing up your team to focus on customizing the areas that differentiate your chat app from the competition. This approach drastically reduces the time and cost required to build, launch, and maintain a chat app.

Chat App Development Steps: Process Overview

With the major architectural decisions made, you're ready to start writing the code for your chat app. It can be helpful to have the steps in the build process mapped out chronologically to avoid overlooking components or dependencies that could cause trouble later. And although some of the details in this process will vary a bit depending on which technical approaches you choose, the high-level order of operations should be fairly consistent. You're of course free to make your own decisions here, and the process doesn't necessarily have to be linear. But for the sake of setting a baseline, here's one popular and proven way to go about the build.

Looking for more technical detail? Check out our library of code tutorials featuring step-by-step instructions to build chat with a variety of different frameworks and approaches.Looking for more technical detail? Check out our library of code tutorials featuring step-by-step instructions to build chat with a variety of different frameworks and approaches.

1. Create a Directory & Install Dependencies

You'll need an environment to house your chat server (back end) and your chat client (front end), so the first step in the development process is to create a directory and install the required dependencies. If you're building chat with JavaScript and Node, for example, you'll need to install Node and set up your project.

2. Build the Front-End Chat Interface & Chat Client

The front end of your chat app can be as simple or complex as desired. If you're using an SDK solution that includes a chat UI kit, you can save time by customizing existing components or even using them as they come. Or, depending on your use case, you may prefer to design your app's UI completely from scratch.

For front-end components, at a minimum you'll need to build A) a simple login screen and B) the chat screen where users edit, send, and receive messages, and C) a list of contacts. Other UI features like a navigation menu can be useful if your app is intended to be more complex like Slack or WhatsApp, but may not be necessary if you're creating an iMessage clone.

The chat screen will need a text input box, a keyboard, and a scrolling display of sent and received messages. If you're building with a chat kit like Stream's, you'll have pre-built components like MessageInput, a custom UI component prop to be shown for the input box, at your fingertips. The login screen will need a form to register new users and a way to authenticate existing users.

3. Create and/or Connect the Back End (Chat Server)

The chat server is responsible for routing messages from sender to receiver and for administering other back-end functions that won't be stored locally on the user's device. If you're building with Stream, you can choose your preferred back-end language among Golang, Python, Node (JavaScript), Ruby, Dart, PHP, or .NET to interact with the Stream Chat API.

On the back end, now it's time to create your user list (contacts), initialize a channel, add new messages to the channel, and create a way to display both old and new messages. Your chat server will need to listen for new messages, render existing messages already in the channel, and push new messages from sender to receiver. Here's what these processes look like if you're building a one-to-one chat app with JavaScript and Stream.

4. Prioritize Feature Expansion Based on User Feedback

At this point, you should have a functioning MVP chat app. You may already have an idea of which advanced features will be necessary, and you can begin to integrate those. But the key to success now is to get a sense of how your users interact with your app. With early access, focus groups, and user surveys/interviews, you can discover and correct any design or functional oversights, then confidently prioritize your dev resources to build out the features that matter most to your growing community of users.

Chat App Development Challenges to Anticipate

Chat app development can be deceptively challenging — the basic concepts and features around instant messaging have been around for so long that we tend to take them for granted and assume they'll be easy to replicate. If you're building a bare-bones personal project to share with a few friends, that might be true, but when it comes to developing, launching, and supporting enterprise-grade chat functionality at scale, even experienced engineers and product managers can hit unexpected roadblocks. Some of these roadblocks are technical in nature, while others crop up on the business side. Teams that anticipate the following chat app development challenges in their earliest planning stages will greatly improve their odds for success.

Chat App Market Fit & Monetization Strategy

As discussed in the competitive analysis section above, the market for dedicated chat apps aimed at the general public is crowded. Leading apps like WhatsApp, iMessage, and Facebook Messenger enjoy broad adoption and boast robust feature sets developed by massive engineering teams over many years. Competing with them will be an uphill battle, but with the right approach to market research and product differentiation, it's not impossible.

For your chat app to break through, you'll need to identify and deeply understand a specific customer problem, make sure your app solves that problem, and then clearly communicate how it solves that problem. Opportunities do exist — familiarity with the needs of a given industry or subgroup of users, for example, can go a long way toward finding product-market fit. A chat app designed to serve stockbrokers and bankers may integrate with fintech tools in an innovative new way, or a telemedicine app may do more than the mainstream chat apps to reassure users that their information will remain secure and confidential.

Norms established by the existing chat giants also dictate, to some degree, which monetization strategies can succeed. Since most of the leaders are free to use, a paid subscription model will likely present a barrier to adoption. In order to add and retain users at a sustainable rate, then, most consumer chat apps will need to offer a "free-forever" tier that still delivers unique value. With the adoption challenge solved, monetization in the form of paid upgrades, in-app purchases, and advertising can follow.

Chat App User Adoption, Engagement, & Retention

Success in the app market requires a growing number of users to not just download your app, but to keep using it regularly. The first hurdle comes during the 24-48 hour period immediately after download: Will users open your app again after this period? A staggering number of apps, even those with high download rates, see user sessions fall off a cliff by day three.

This retention problem underscores the importance of investing in a stellar chat app user experience. The UI needs to be so simple and intuitive that even inexperienced users will be able to figure out the basics of sending and receiving messages in seconds. They'll need to find each other easily, ideally importing or syncing existing contacts. And beyond ease of use, the combination of features, polish, and overall fun factor will need to conspire to keep people coming back.

For apps that serve a more specific use case than general social messaging (think telemedicine, edtech, ecommerce, gaming, or dating, for example), in-app chat has been proven to increase app engagement. Even if a more general messaging application is your goal, there's a lesson to learn here: The more your app is associated with a specific need, the better its chances of achieving strong adoption, engagement, and retention.

The bottom line is that the key to a successful chat app build may not be an engineering breakthrough. Market research and thoughtful design are critical to the planning process, even before you begin to architect the build itself. We recommend outlining a clear rationale for your chat project, with concrete goals in terms of adoption, engagement, and retention that can be tracked after launch and used to further optimize the experience.

Chat Performance & Reliability

Another significant risk in creating a chat app is the possibility that your team will sink significant time and resources into a product that ultimately doesn't function as expected. Performance issues detract from the real-time experience of instant messaging, with perceptible latency, undelivered messages, or app crashes frustrating users. The worst-case scenario involves rewriting or refactoring huge swaths of code, diverting valuable dev resources, and incurring massive unplanned costs. Preventing such issues requires both the right architectural decisions and the right infrastructure from the beginning.

Ideally, features and updates should be developed in parallel to avoid unnecessary dependencies, where a problem with one feature breaks another. One way to achieve parallel development is to build or integrate a unified API back end, with which each individual component communicates. A proven third-party solution can go a long way toward ensuring a reliable, high-performing chat experience.

Scalability

Scalability is one of the key factors that separates enterprise-grade chat products from inferior competitors. Scalable chat infrastructure goes hand-in-hand with performance and reliability, and it's difficult to fix late in the game. The problem is that early in the development process, it can be hard to imagine hitting ambitious usage goals. It's tempting to prioritize building out complex functionality instead of getting the fundamentals of scale right at the proof of concept or minimum viable product (MVP) stage. But realistically, if your chat app is going to succeed in the long term, it needs to be able to handle a high volume of concurrent sessions, channels, and users.

Without some foresight, you set yourself up for a massive infrastructure migration complete with degraded performance and significant downtime right as your chat app is taking off. We've seen plenty of promising chat apps fail once they're hit with more concurrent sessions than expected. Even Capital One, which invested a massive amount of resources to develop one of the most advanced fintech chatbots on the market, ran into rate limit issues when it came time to scale.

Scalable chat requires a thoughtfully configured, highly available, and highly resilient infrastructure setup — for most teams, this means turning to one of the major cloud infrastructure-as-a-service (IaaS) providers: AWS, GCP, or Azure. As your chat app grows, a dedicated DevOps team should handle scaling, maintenance, and troubleshooting of your pipeline and production infrastructure. Response times to deploy scalable infrastructure, such as automatically spinning up a new server in advance as loads increase, can be further minimized by automating repetitive DevOps tasks in an infrastructure-as-code approach.

Cross-Platform Development

Today's chat apps must be accessible for users on a variety of device types and operating systems. These include iOS, Android, and web at a minimum, though desktop apps for Mac and Windows can be nice to have as well. It's easy enough to build chat for a single platform, but time, cost, and technical challenges multiply when you need a consistent experience across all of these platforms. Each platform presents its own unique obstacles and requires a different developer skill set. You'll need to invest equally in development across each platform or risk delivering a disappointing and inconsistent experience.

Pre-built API solutions can help solve this problem by providing cross-platform chat SDKs, which make it possible to succeed without hiring a dedicated expert in each platform. This means engineering teams can use the language of their choice, like JavaScript, Python, Ruby, Go, Swift, or PHP, instead of uprooting their preferences.

Security & Compliance

As the public grows more attentive to privacy and security issues, interest in chat apps that proactively solve these issues (and effectively communicate their efforts) will increase. We've already seen news coverage of questionable privacy practices drive some users away from mainstream apps like WhatsApp and onto smaller chat platforms unaffiliated with Big Tech, like Signal, Telegram, and Threema. And, if your chat app intersects with an industry that regularly deals with sensitive information, like payment processing or healthcare, it will need to meet compliance requirements. Broad frameworks like GDPR, ISO 27001, and SOC 2 are universally relevant, with industry specific frameworks like PCI DSS and HIPAA adding additional security requirements.

At a minimum, all data will need to be encrypted in transit and at rest. True end-to-end encryption, while not always officially required, is a good idea. On top of that, appropriate identity management measures like multi-factor authentication (MFA) and password complexity and rotation requirements ensure only the right people can decrypt private messages.

Final Thoughts: Choosing a Chat Technology Provider

For many chat and messaging applications, most of the complex technological challenges covered in this guide can be simplified by integrating pre-built chat technology into your own custom application. A chat API and SDK solution reduces technical uncertainty and increases the odds that your app will launch successfully on time and on budget. And you don't have to give up on the prospect of building the next great truly custom chat app in order to take advantage of these gains in efficiency — with a white label solution like Stream, you integrate the chat functionality that makes sense for your use case while retaining total control over the look, feel, and experience your product delivers.