Grosz: everything you own, in one number.

The problem

People who earn, save and invest in more than one currency have no single place that answers the simplest question: how much do I actually have? Banking apps show one bank. Spreadsheets go stale. Most budgeting apps assume one currency and want your bank password.

What we built

Grosz puts every account, every currency and every investment next to day-to-day spending, and adds them up into one net-worth number.

• Every currency, one total. Balances in any currency, converted into the one you think in.
• Investments next to spending. Portfolios live in the same view as cash and cards.
• Four ways to add a transaction: say it, scan the receipt, let bank alert messages do it, or tap it in.
• A Telegram bot for adding and checking transactions without opening the app.
• Shared wallets for couples, families and flatmates.
• An AI assistant that knows your numbers and answers questions about your own spending.
• No bank passwords. The app is locked with a PIN or Face ID.
• Five languages: English, Polish, Czech, Ukrainian and Russian.

How it's built

One backend serves every client. It's a Cloudflare Worker written in TypeScript with Hono and an OpenAPI contract, talking to PostgreSQL through Cloudflare Hyperdrive. The business logic is written once and shared by three surfaces: the mobile and web app, the Telegram bot and an API-key layer for integrations.

The app is React Native with Expo, one codebase for iOS, Android and the web. Money is handled with decimal arithmetic end to end, never floating point. The public landing pages are prerendered in five languages with per-language social cards and a sitemap.

What clients get from it

Grosz is where we solved multi-currency money handling, receipt and message parsing with AI, Telegram bots, app store releases and multilingual SEO under real-world constraints. If your product touches money, documents or several platforms, we've done that work before. See our custom software development and AI integration services.