There are many ways to build a custom chat app, depending on your skills, preferences and goals. Based on web search results, some of the common steps are:
Choose a platform and a programming language for your app. For example, you can use Android, iOS, web, or cross-platform frameworks. You can also use languages like JavaScript, Python, Java, Swift, etc.
Decide on the features and functionalities of your app. For example, you can include text, voice, video, file sharing, emojis, stickers, group chats, etc.
Design the user interface and user experience of your app. For example, you can use wireframes, mockups, prototypes, etc. to create a layout and a flow for your app.
Implement the backend and frontend of your app. For example, you can use cloud services, databases, APIs, libraries, frameworks, etc. to build the logic and the presentation of your app.
Test and debug your app. For example, you can use tools like Firebase Test Lab, Espresso, XCTest, etc. to check the performance and functionality of your app.
Publish and market your app. For example, you can use platforms like Google Play Store, App Store, etc. to distribute your app. You can also use strategies like SEO, social media, ads, etc. to promote your app.
Some of the web search results that can help you with more details are:
How to build your own real-time chat app - freeCodeCamp.org1
Build an app with the Teams platform - Microsoft Support2
Building an Android Chat App from Scratch – Complete Guide - Contus Tech3
How to Make a Messaging App: The Full Guide - Topflight4
Chat & Messaging App Builder - Create a Chat App - Shoutem5
I hope this helps you get started with your chat app project. 😊