Zahlbob

A shared-expense tracker for people who already trust each other. Put a group together, log what everyone spent, and Zahlbob works out who owes what — netted down to the fewest transfers that square the group up, or left un-netted if you'd rather the payments match the debts people actually remember.

See docs/project.md for the motivation and design decisions behind it.

Stack

• Frontend: Angular (standalone components, signals), organized as domain-scoped libraries. See docs/frontend.md.
• Backend: Rust (Axum + ConnectRPC, sqlx/Postgres), organized as a Cargo workspace of domain crates. See docs/backend.md.
• Auth: Zitadel (OIDC).

Getting started

Prerequisites are managed via mise.

just setup           # install required tools via mise
just start infra     # start local infra (Postgres, Zitadel, Caddy) via podman compose
just start migrations  # apply database migrations

Infra takes a bit to become healthy (Zitadel in particular) — wait and retry if the next step fails immediately.

Zitadel one-time setup

Fresh infra needs a Project + OIDC Application (for a client_id) and at least one login account before the app is actually usable - none of that exists until you run:

just setup zitadel                 # or: just setup zitadel 192.168.50.82 for infra-devbox

This creates the app registration (writing client_id to app/client/public/env.js, gitignored, picked up automatically by app.config.ts - see index.html's env.js comment) and self-registers dev@md.local / _Password1 (for you).

Run the backend and frontend in separate terminals:

just start backend    # cargo run -p zahlbob, raw HTTP on 0.0.0.0:5421
just start frontend   # ng serve, raw HTTP on 0.0.0.0:5431

Both run as plain native processes with no TLS of their own - Caddy is what terminates HTTPS and proxies to them (host.containers.internal:5421/:5431, see config/infra/caddy/Caddyfile), so the app itself is browsed at https://localhost:5430, not :5431. The raw ports still work directly over http://localhost:5421/:5431 for local-only debugging (e.g. the "ng serve" launch config in .vscode/launch.json) - that's fine since localhost is a secure context on its own, but don't use the raw ports from another machine, since that's exactly the insecure-context case Caddy exists to avoid.

Testing

just test        # see config/scripts/test.just for available targets

Repository layout

• app/ — application entry points (e.g. the backend server binary)
• domain/ — vertical slices (auth, group, landing, shared, tracing), each with its own frontend/, backend/, and api/ as applicable
• docs/ — architecture and design documentation
• config/ — local dev tooling (just recipes, infra compose files)