Building Secure Web Chat Apps

5 min read Piotr Suwala on Mar 26, 2024

In an era where real-time communication is the norm, the demand for speed and convenience has never been higher. However, this convenience has also introduced potential security threats such as eavesdropping and data breaches. It is predicted that cybercrime will cost the world over $6.5 trillion annually by 2025. This underlines the importance of secure web chat applications like WhatsApp, iMessage, and Telegram which use authentication to prevent hackers from obtaining sensitive user data, even in the event of a data breach.

What are secure web chat apps?

Secure web chat apps, also known as secure messaging apps, are renowned for their robust security measures, including end-to-end encryption and Transport Layer Security (TLS). These security features are fundamental in both iOS and Android operating systems, ensuring the functionality of messaging apps on mobile devices. End-to-end encryption ensures that messages are only decipherable to the communicating users, safeguarding data from eavesdropping or data breaches. TLS, also referred to as Secure Socket Layer or SSL, secures communication between the chat application and the backend server.

Renowned secure web chat apps such as Signal, Telegram, and WhatsApp are well-known for their stringent encryption measures. They employ security methods like two-step verification and self-destructing messages to ensure user data security. Additionally, these applications also prevent common JavaScript vulnerabilities such as XSS attacks, protecting users' personal data from phishing attempts or unauthorized access to their finances.

Secure vs. encrypted web chat apps

While encryption is a significant aspect of security, it's not the be-all and end-all. Secure web applications should implement comprehensive data protection layers, such as up-to-date access control and permissions mechanisms. Emerging technologies like biometric authentication, multi-factor authentication, and Role-Based Access Control (RBAC) have significantly enhanced the security matrix of the modern web chat applications.

Types of security for web chat apps

As cybersecurity threats evolve, the need for adaptive and resilient security measures has never been more critical. Messaging platforms face emerging threats such as AI-powered attacks, ransomware, and state-sponsored hacking which pose severe risks to web chat application security.

For instance, Deepfake technology, which uses algorithms for image synthesis, has emerged as a potential threat to data privacy. Malicious actors can misuse this technology to impersonate trusted individuals or organizations, leading to potential data breaches or fraudulent activities.

XSS attacks on chat apps

In terms of chat application security, since most of the content is dynamic and generally created by users, it’s safe to assume that at some point, one or more malicious users are going to appear and wreak havoc. These attacks are known as Cross-Site Scripting (XSS) and if handled incorrectly, these types of messages can end up as scripts executed on end users’ machines, ultimately leading to stolen credentials.

Man in the middle attacks (MITM) on chat apps

A man in the middle attack (MITM) is a practice in which two people think they communicate privately with each other but they’re being eavesdropped on by a third party without their consent. The third party may alter their messages in order to receive important information or they may simply keep collecting information.

Lack of end-to-end encryption on chat apps

End-to-end encryption is a system where only communicating users can read messages. The idea is that everyone—including Internet service providers, the company behind the app or malicious actors—cannot read the messages unintended for them as long as they don’t possess the encryption/decryption key.

How to build a secure app for chat on web

Now that we’ve covered the different types of security features and functionality of modern web chat apps, let’s take a look at the best practices for ensuring app security.

Best practices for building secure web chat apps


Nowadays, there are virtually no instances where TLS/SSL protocol should not be used and a web chat app is a primary example where a secure transfer protocol is most beneficial. When a safe protocol is being used, only the server and a client may view the content in plain text. That prevents Man in the Middle attacks for as long as the private certificate from the server is not stolen.

Sanitize uncertain content

Because users can often type whatever they want, it’s just a matter of time before someone tries to inject custom JavaScript code. You can display users’ messages as plain text but sometimes you want rich content to be available, such as bold text fragments or italic text. Stripping this type of content would limit your users’ creativity.

If handled correctly by the party responsible for the chat app, it should be stripped of its script content or rendered purely as text for example:

But if handled incorrectly the result might end up like this:

Build end-to end-encryption

When building an end-to-end encryption service, your content needs to be encrypted on the client side before being sent. The server must not have the cipher key and you need to decrypt your message upon receiving it also on the client side. If at any point your server application knows the cipher key or implements a back door, then you risk leaking unsecured content which can cause a data breach.

Building a secure app for chatting on web

Now that you’re familiar with the basics, you can start building! Here’s a list of some additional tips to help get you started:

1. It’s typically a good idea to use an npm (package manager) library called DOMPurify that removes all malicious scripts from your messages.

2. You’ll want to use a frontend framework that is robust enough to handle this type of issue. React is a great example where using the default data binding with curly braces ({}) automatically escapes values inserted inside them which protects against XSS attacks.

3. Implement a secure algorithm for message encryption that is difficult or nearly impossible to break, for example a 128-bit AES algorithm. AES is approved by the U.S. National Security Agency (NSA) for top secret information when used in an NSA approved cryptographic module.

Using PubNub in your secure web chat app

PubNub fits very well with security concerns, as it supports the TLS protocol by default and allows for end-to-end encryption using AES (Advanced Encryption Standard) that provides symmetric encryption to guarantee end-to-end data security with the key being defined by the developer. The module supports not only plain messages but file encryption as well.

Getting Started with PubNub for your web chat app

If you're considering leveraging PubNub's features for your web or mobile app, you'd be in good company. Many businesses have found success in using PubNub's robust set of features for their chat applications. Remember, ensuring the security of your web chat application isn't just about integrating security measures. It's about building trust with your users, knowing that their data is protected with the best security protocols and cybersecurity practices available.

At every step of creating a secure web chat app, PubNub is with you. From the implementation of stringent security protocols to making sure your app remains reliable and real-time, our platform is designed to guide you to success. Our APIs are designed to provide secure and efficient solutions for your application needs but you don't have to take our word for it. Explore what our satisfied customers have to say and get started with building your secure web chat application with PubNub today.

To get started, all you need to do is create a PubNub account (which is free)