Nomad Expenses: Multi-Currency Travel Expense Tracker

Project overview

Nomad Expenses is a mobile-first travel expense tracker for long trips across many countries. You log an expense in the currency you paid, in about 3 taps. The app converts it to euro at the exchange rate for that day, then shows what the whole trip has cost by category, by month, by country and by trip leg.

I built it for my own journey: 9 months on the road through 9 countries, from Chiang Mai to Almaty, starting in December 2026. That means 9 local currencies plus flights and bookings charged in euro or dollars. A spreadsheet stops being practical on day 3 of a trip like that. The well-known budgeting apps want an account, a subscription and my spending data on their servers. So I built a small private web app that I host myself, with one password, one database and no tracking.

The project sits closest to SaaS development and custom Next.js product engineering. It follows the same approach as NomadWealth, my self-hosted net worth app: the owner keeps the data and the product stays small enough to deploy in minutes.

The challenge

Every new currency makes one simple question harder to answer: what has this trip cost so far? The app had to answer it from data entered in seconds, on a phone, often on a slow connection, without sending that data to anybody else.

What was delivered

I designed and built the whole product: the data model, the currency conversion, the 4 screens, the card interface, the read-only share view and the deployment. The first version shipped as a working app that anybody can deploy to their own Vercel account in under 5 minutes.

The amounts in these screenshots are sample data.

Core functionality included

Key architecture decisions

The guiding rule was to keep the product small. It has one user, one password and one database, so every feature that a multi-user product would need was left out on purpose. 4 decisions did most of the work.

The exchange rate lookup carries a currency and a date and nothing about the person asking. The first 2 sources keep daily history, so an expense entered a week late still gets the rate for the day it happened. The third source only knows the latest rate and acts as the last fallback.

Results and outcomes

The result is a finished, installable travel expense tracker that answers the question it was built for. Open the overview and the cost of the trip is there in euro, for the whole journey or for a single country, built from entries that take seconds to make.

Technology used

Nomad Expenses is built with Next.js 16 and the App Router, React 19 and TypeScript, styled with Tailwind CSS 4 in a monochrome card design with Lucide line icons. Data access uses Drizzle on a Neon Postgres database, with server actions for sign in, expenses, legs and share links. Exchange rates come from the fawazahmed0 currency data set through 2 delivery networks, with open.er-api.com as the last fallback. The app deploys to Vercel and installs on a phone home screen through a web app manifest.

The delivery is most relevant to SaaS development, mobile-first web apps and custom development where speed and privacy matter more than a long feature list.

Next steps

This case study covers the first version, built before the trip begins. The roadmap comes from the route itself: offline entry that syncs when a connection returns, for the Fann Mountains and Song-Kul, then budgets for each leg and category with the remaining amount, then receipt photos attached to an expense.

If you need a small focused web app, an internal tool or a first version of a product that people can use on a phone, the most relevant starting point is SaaS development. You can also tell me what you are building and I will recommend the next practical step.