Sebastien Castiel

Create your Net Worth Tracker with Kotlin

Published in 2022

Tracking your Net Worth is the best way to stay aware of your personal financial situation. It doesn’t have to be boring or complicated…

If you know how to code, you can now make it fun!

What is the Net Worth and why should you keep track of it?

Your net worth is the total value of your assets (cash, investments, house value…) minus the value of your liabilities (i.e. debts: loans, mortgage, credit card balance…). By knowing at each time how much you own, you can plan goals and see how close you are to achieving them.

Tracking your net worth can be as simple as listing all your assets, your liabilities, and making some additions and subtractions. But what if you own assets in different currencies? Or what if you own stocks and don’t want to go manually fetch their value? This is when building your own tracker will help you!


  1. Your local development environment
  2. Your first net worth tracker
  3. Displaying table reports in the terminal
  4. Adding metadata to accounts
  5. Building a better command-line application
  6. Accounts in different currencies
  7. Dependency injection and global configuration
  8. Stocks and cryptocurrencies
  9. Resilient API calls with a cache and a retry mechanism
  10. Reports in the web browser

Why should you read the book?

With this book you’ll learn how to:

Why Kotlin? What if you don’t know the language?

Kotlin is a modern language, very easy to learn, that lets you write very expressive code. Using it, you can focus on the business logic you want to implement, rather than the technical details such as dealing with memory.

If you have never used it but already know another language (e.g. Java, JavaScript, Ruby…), here is a secret for you: I didn’t know Kotlin before I started creating my net worth tracker 🤫! It was a great project to learn the basics, and I was never blocked by language technicalities.

Hi! I’m Sebastien Castiel 👋

I’m a French developer expatriated in Montreal.

I’m passionate about personal finance. I work for a Canadian fintech company, and I have used several languages professionally for several years now.

What if I don’t like what I bought?

If you are not satisfied with the book, I offer you a 30-day money-back guarantee, no question asked.

Just shoot me an email at