Kredite

A small, self-hosted loan portfolio tracker. Enter your loans once — principal, interest rate, monthly payment, start date — and get a live overview of balances, amortization schedules, total interest cost, and which loan to pay off first.

Built with Svelte 5, Chart.js, Express, and SQLite. Ships as a single Docker container.

Note: The user interface is currently in German.

The problem

If you have more than one loan — a mortgage, a car loan, a family loan — the numbers that actually matter are surprisingly hard to see:

• How much do I still owe across all loans, right now?
• How much interest will each loan cost me in total, and how much is still ahead of me?
• If I have spare money, which loan should I pay down first?
• When will I actually be debt-free?

Banking apps show one loan at a time, and spreadsheets rot. Kredite computes full amortization schedules from just four numbers per loan and answers these questions on one page.

Who it's for

• Households with several loans who want a single, honest overview instead of scattered bank portals.
• Self-hosters who don't want to hand their financial data to a SaaS — everything stays in one SQLite file on your own machine.
• Anyone deciding where an extra repayment helps most: loans are ranked by remaining interest cost.

Features

• Portfolio dashboard: total balance, monthly payment load, total and remaining interest, projected payoff date.
• Full amortization schedule per loan, computed on the fly (no schedule data to maintain).
• Balance-over-time chart for the whole portfolio (Chart.js).
• Payoff priority list — loans sorted by how much remaining interest they will still cost you.
• Handles interest-only loans (payment = 0) explicitly instead of producing nonsense numbers.
• Single SQLite file as the only state; trivial to back up.

Installation

Option 1: Docker Compose (recommended)

git clone https://github.com/andersennl/kredite.git
cd kredite
docker compose up --build

The app is then available at http://localhost:3000. The SQLite database lives at /data/kredite.sqlite inside the container; by default it is stored in ./data on the host. Set KREDITE_DATA_DIR to use another host path:

KREDITE_DATA_DIR=/path/to/volume docker compose up --build

Option 2: Local development

Requires Node.js 22 (the version the Docker image uses; better-sqlite3 11.x does not build on newer Node majors).

npm install
npm run dev

This starts the Express API (with node --watch) and the Vite dev server concurrently. For a production build: npm run build && npm start.

Configuration

Variable	Default	Purpose
PORT	3000	HTTP port of the server
DATA_DIR	./data (/data in Docker)	Directory for kredite.sqlite

There is no authentication — run it on a trusted network or behind a reverse proxy with auth (see roadmap).

Tests

The financial core (amortization, portfolio totals, payoff priority, formatting) lives in src/lib/calculations.js and is covered by Vitest:

npm test

If you touch the calculation logic, add a test case — that file is the part of the project where silent mistakes cost real money.

API

The server exposes a small JSON API, used by the frontend and usable for scripting:

Method	Path	Description
GET	/api/loans	List all loans
POST	/api/loans	Create a loan
PUT	/api/loans/:id	Update a loan
DELETE	/api/loans/:id	Delete a loan

A loan is { name, startDate, principal, annualRate, monthlyPayment }. All schedule math happens client-side from these five fields.

Roadmap

Rough order; none of this is promised. Open an issue if one of these matters to you.

• English UI / i18n — the calculations are locale-independent, the labels are not yet.
• Extra repayments (Sondertilgungen) — one-off payments that recompute the schedule from that point.
• Fixed-interest periods (Zinsbindung) — model a rate change after N years instead of assuming one rate for the whole term.
• CSV/JSON export of loans and schedules.
• Optional authentication for exposing the app beyond localhost.
• Prebuilt container image on a registry.
• Upgrade better-sqlite3 to a version that builds on current Node majors.

Contributing

Issues and pull requests are welcome. Keep it small and focused:

1. Fork, branch, make your change.
2. npm test must pass; add tests for any change to src/lib/calculations.js.
3. Open a PR describing what problem the change solves.

License

MIT © Nikolaj Andersen