Build a Real-Time In-App Chat in Android Using PubNub (Kotlin + MVVM) – Complete Tutorial Series

 


Want to add real-time chat to your Android app without building an entire backend?

In this tutorial series, you'll learn how to create a modern, scalable real-time in-app chat using Kotlin, the MVVM architecture, and PubNub — a robust platform built specifically for real-time communication.

This post is your go-to index for the entire series. I’ll update it with links as each part goes live. Bookmark it now!

Why PubNub?

PubNub is a real-time communication platform that removes the complexity of building low-latency messaging and presence systems. Here’s what it offers out of the box:

🔧 Core Features for Android (Kotlin)

  • Real-Time Messaging – Send and receive messages across any number of devices instantly.
  • Message Persistence – Store and retrieve message history.
  • User Presence – Detect when users come online or go offline.
  • Typing Indicators – Show “User is typing…” live updates.
  • Channel Groups – Organize multiple chatrooms or group threads.
  • Push Notifications – Integrate with FCM to alert users of new messages.
  • Access Manager (PAM) – Control who can publish/subscribe to channels.
  • File & Media Sharing – Send files or images directly within chat.
  • Message Reactions & Metadata – Add context to any message.
  • Low-Latency & Scalability – Designed to support millions of messages per second.

Tutorial Series Index

✅ = Live  🔄 = Coming Soon (links will be added as they're published)

✅ 1. Introduction

What we’re building,why real-time chat matters, and why PubNub is a solid choice.
Read Part 1

🔄 2. Project Setup (Kotlin + MVVM + PubNub SDK)

Create a new Android project, add MVVM structure, and connect to PubNub.

🔄 3. PubNub Initialization & Basic Messaging

Set up PubNub in the repository layer, and start sending/receiving basic text messages in real time.

🔄 4. Designing the Chat UI

Build a clean chat screen using RecyclerView, message bubbles, and input fields.

🔄 5. Implementing Message Sending

Capture user input, structure message payloads, and publish them through PubNub.

🔄 6. Subscribing & Receiving Messages

Listen for messages in real time and update the UI reactively using LiveData.

🔄 7. Chat History & Persistence

Fetch previous messages using PubNub’s history API and support pagination.

🔄 8. Presence & Typing Indicators

Show when users are online/offline and when they’re actively typing.

🔄 9. Reconnection & Error Handling

Handle network issues gracefully and ensure a reliable chat experience even under bad connectivity.

🔄 10. File & Image Sharing

Upload files, share image URLs in messages, and preview them in the chat window.

🔄 11. Push Notifications with FCM

Set up Firebase Cloud Messaging to alert users when messages arrive in the background.

🔄 12. Group Chat & Multi-Channel Support

Use PubNub’s channel and channel group system to manage multiple chat threads and rooms.

🔄 13. Security with Access Manager (PAM)

Implement user-level access control and protect your keys from unauthorized use.

🔄 14. Reactions, Metadata & Message Enrichment

Use PubNub’s objects and metadata features to add reactions, timestamps, and user info to messages.

🔄 15. Testing, Debugging & Wrapping Up

Final tweaks, testing best practices, and extending the app beyond chat (voice, bots, analytics).

Tech Stack

  • Language: Kotlin

  • Architecture: MVVM

  • Platform: Android

  • Libraries: PubNub SDK, LiveData, ViewModel, RecyclerView, FCM (optional)

  • Extras: Firebase (optional), Glide, Retrofit (for media handling)

Stay Updated

Follow me on Medium or bookmark this series to stay updated as each part is released.

Questions or Ideas?

Got a use case in mind? Want to see a certain feature added?
Drop a comment below, or connect with me on X (formerly Twitter) @revansiddappa1. Let’s build this together — one feature at a time.

Are you ready to bring your Android app to life with chat? Let’s get started! 


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