🛠 Development diary: the app isn’t working alone

Martin Fowler makes the case for starting with a monolith: build the application first, then split it into services once the boundaries between responsibilities become clearer. Coordinating separate services adds work—a meaningful cost when you’re building an MVP.

But a finance app learns a lot about the world from outside sources. Exchange rates, asset prices, account balances and transaction histories all come from different places.

Each brings its own questions. Getting the data doesn’t automatically give you a clear picture. How fresh is it? What happens when a source is unavailable? Why do two providers report different values?

All of this can live inside a monolith. But working with external data has its own requirements and pace of change. That’s why, even at this early stage, we’re separating some of these responsibilities into independent services in JAB47.

Microservices or perhaps something larger—the name matters less than the work. We already have to think through how these parts communicate, exchange data and handle failures.

Yes, that adds work before the MVP is even released. It also gives us room to develop those services independently and connect new sources without turning every change into a rework of the whole app.

We’re designing JAB47 around people who hold different kinds of assets: money in several currencies, securities, crypto and other investments. Handling that variety is part of the product’s foundation.

There’s another possibility here, too: data collected and made understandable could be useful to you in its own right. We’ll share more about how we plan to make it available as that takes shape.

#JAB47 #BuildInPublic