Grundstücksfinder

Grundstücksfinder is a self-hosted search tool for German real-estate parcels. It imports official open data ("Grundsteuer") published by German states, stores it in Postgres, and lets you search parcels by postal code, municipality, and area (m²) through a Blazor Server web UI — with geocoded map markers via OpenStreetMap/Nominatim.

Currently ships with an importer for North Rhine-Westphalia (NRW). The import pipeline is built around a pluggable IPropertyImporter interface, so adding another Bundesland (or country) is a matter of writing one importer class — no changes to the shared import, storage, or search code required.

Features

• Search parcels by PLZ, Gemeinde, and min/max area
• Map view with geocoded markers (Nominatim, cached to respect its usage policy)
• Automatic daily import of new open-data releases, deduplicated per dataset/file/version
• Multiple data sources can coexist without one import wiping another's rows
• Import history (ImportLog) shown per source

Quick setup

Run it (Docker Compose)

Requires Docker and a web external network for Traefik (or drop the Traefik labels/network in docker-compose.yml if you don't use it).

1. Copy the env template and fill in real values:

   cp .env.example .env

   Variable	Meaning
   DB_PASSWORD	Password for the homelocator Postgres user, shared by app and db
   DOMAIN	Public hostname Traefik should route to this app
   GITHUB_REPOSITORY_OWNER	GitHub user/org owning the ghcr.io/<owner>/grundstuecksfinder image

2. Start it:

   docker compose up -d

   The app listens on port 8080 behind Traefik and connects to the bundled postgres:17-alpine service. On first startup it downloads and imports the current NRW dataset (this can take a few minutes); the daily import check then runs at 03:00 UTC.

Local development

docker-compose.dev.yml only starts a local Postgres instance (hardcoded dev password, no .env needed):

docker compose -f docker-compose.dev.yml up -d
cd Grundstuecksfinder
dotnet run --project Grundstuecksfinder

Config for local dev lives in Grundstuecksfinder/appsettings.Development.json (ConnectionStrings:DefaultConnection, Import:Nrw:*). To skip waiting on the real NRW download while developing, set EnableDevSeeding to true (in launchSettings.json or as an environment variable) — this seeds a handful of fake parcels from part.csv (or a single hardcoded fallback row) instead of hitting the network.

Adding another region's importer

Implement IPropertyImporter (see Services/Importers/Nrw/NrwPropertyImporter.cs for a CSV-based example) and register it in Program.cs:

builder.Services.AddScoped<IPropertyImporter, YourRegionPropertyImporter>();

The shared ImportOrchestrator/PropertyBulkWriter handle dataset dedup, per-source deletes, and the Postgres bulk write — your importer only needs to know how to discover and fetch its region's data.

Running tests

Integration tests spin up Postgres via Testcontainers, so Docker must be running:

dotnet test --project Grundstuecksfinder.Tests

License

Licensed under the GNU Affero General Public License v3.0 (AGPL-3.0-or-later).