A person’s financial life is usually scattered across places that do not talk to each other: one bank’s app, another bank’s statement PDF, a broker’s portal, a credit card invoice, and a spreadsheet kept by hand to make sense of the rest. Nothing reconciles, so where did the money go? and where will I be in six months? take an afternoon of manual work to answer.
Fortuna exists to answer them from a single ledger. It is built for individuals and households who do not want to hand that data to a service they do not control, so it is self-hostable: it runs on your own machine or server, stores no bank credential, and computes money with exact decimal arithmetic rather than floating point.
The API holds the data and the rules. On its own it answers in JSON, and nobody reads their finances in JSON, so Fortuna UI is the application a person actually uses. The API owns the domain, the money and the integrations, and the UI owns the experience.
API (.NET)
ASP.NET Core on .NET 10 with C# 14, in a layered Domain, Application, Infrastructure and Presentation structure. Data lives in PostgreSQL for shared deployments, with SQLite as an alternative for local use. A Dockerfile builds its container image.
Native core (Rust)
A Rust library, in the API repository, with its own SQLite storage. It exposes the API’s operations through a C interface so the desktop app can run offline, in process. It does not implement everything the API does yet.
UI (Flutter)
One Flutter code base for the web, Windows, Linux and Android. It reaches the API over HTTP, or, in desktop offline mode, the native core through FFI. The interface is still being completed.
Signs in through Heimdall
In connected mode, identity is not Fortuna’s. Fortuna is a client system of Heimdall, the identity service from the same author, and it forwards sign-in to Heimdall and trusts the tokens it issues. The desktop offline account is the one exception.
License
The Artur Rios Attribution License: free and open source, so you may view, use, fork, modify and extend it, crediting the author. Both repositories carry the same license, and the license file has the terms.