German state geoportals compared

Three data questions before buying

A Geoportal, an official geodata portal, is rarely just a map. It combines Geobasisdaten, official base geodata, planning information and specialist layers maintained by different offices. For a plot, answer three questions separately: what is legally buildable, where are the parcel and buildings, and which land value is a useful comparison?

The states offer different entry points. One interface may lead directly to Bauleitplanung, planning data, and ALKIS, the official cadastral information system; another may point to a separate Bodenrichtwert, standard land value, service or municipal platform. The portal name matters less than the data date, metadata and responsible office.

Read the development plan correctly

A map service may show the outline of a development plan while only linking or summarising its written rules. To assess buildability, read the plan drawing, written provisions, statement of reasons, local by-laws and amendments together. Under § 10 BauGB, the municipality adopts the development plan as a by-law and remains responsible for binding planning.

The query under § 30 BauGB therefore starts with the exact Flurstück (official cadastral parcel) number, and the correct plan version. A coloured layer may show a building line, use category or overlapping rule, but cannot reliably explain whether an exemption, Baulast (public-law building obligation) or exception applies. The zoning and buildability review needs the original documents.

Open the full page

ALKIS is geodata, not the land register

ALKIS describes parcels, location names, actual use and often building outlines. It is highly useful for identifying a plot, but proves neither ownership nor every private boundary. Ownership and charges are recorded in the Grundbuch, the land register; access requires a legitimate interest under, among other rules, § 12 GBO.

A line on an ALKIS screen is not a boundary determination. Scale, generalised geometry, old surveys or an overlay with aerial imagery can make the display inaccurate. For a boundary fence, planned garage or subdivision, involve the responsible survey office or a publicly appointed surveyor. The land register and ALKIS comparison shows which question each system can answer.

Open the map full size

Bodenrichtwert as a comparison value

Under § 196 BauGB, Bodenrichtwert describes the average land value for a Bodenrichtwertzone, a standard-land-value zone. It is a statistical reference, not the market value of the individual parcel. Shape, servicing, planning rights, slope, contamination and easements can change the actual value substantially.

The reference date matters. A current figure can relate to a valuation date before the purchase offer. Under § 199 BauGB and related rules, Gutachterausschüsse, valuation committees, work with zones and value-determining features. A free map extract does not replace information containing the full zone characteristics.

The sixteen state geoportals

The overview gives the official entry point recorded in the datasets for plot checks. Services do not work identically. One state opens a map viewer; another opens metadata with links to ALKIS, planning or Bodenrichtwert services.

Stand: August 2026. The table identifies the state-wide entry point, not a binding answer for a specific parcel. The responsible service or municipality controls the plan version, boundary and standard-land-value zone.

Open the full page

Why the states offer different entry points

Geodata is organised federally and by subject. State law determines infrastructure and access points, while cadastral offices, valuation committees and municipalities provide their own datasets. Similar information can therefore sit under different menus, or municipal planning may be reachable only through a search map.

City-states have a different administration from territorial states. In Hamburg, Berlin and Bremen, many tasks sit with state or district offices; elsewhere the municipality must provide the binding plan version. A state viewer does not remove that boundary of responsibility.

Check metadata and map date

Before saving a screenshot, record the data date. Check update date, scale, coordinate system, accuracy, service operator and layer licence. With WMS or tile services, the viewer shows a rendered image; metadata explains which object class lies behind it.

For a development plan, record plan name, adoption date and amendment status. For ALKIS, note parcel number, Gemarkung, cadastral district and extract date. For Bodenrichtwert, record valuation date, zone, development status and plot characteristics. This combination makes a later review traceable. Access and provision rules under § 1 and § 3 of the relevant geodata law may differ between states.

A service can be technically reachable and still show old or incomplete data. Check whether the municipality has a newer plan, the survey office an updated extract or the valuation committee a corrected zone. The map is an entry point, not the final authority.

A green symbol or coloured area is not a legal assessment either. Protected areas, flood zones, contaminated sites and monuments may come from different services. The state monument rules and the monument-area search need an additional check with the responsible office.

Workflow for a purchase plot

Start with Gemarkung, Flur and Flurstück. Save the ALKIS extract with its date, open planning data and read the written provisions. Then check the Bodenrichtwert zone, servicing information, protected areas, flood and contamination indicators. This order prevents a plausible land value from obscuring the more important question of usable development rights.

For an unplanned built-up area, § 34 BauGB matters; for the outer area, check § 35 BauGB. An agricultural or nature-protection layer may require an additional approval. Permit-free ancillary structures and rules for sheds and fences help only after the planning status is clear.

Financing also includes land transfer tax by state, tax rates on a purchase, purchase costs and costs before notarisation. Bodenrichtwert is not a substitute for a valuation or price negotiation.

Bring plot data together before buying. A GrundCheck report puts parcel, planning status and visible public-law issues into a reviewable sequence. Check a property.

For boundary questions, add setback rules by state and boundary and survey checks.

Compare the map with original sources. The record stays clear about which statement comes from ALKIS, planning law or Bodenrichtwert. Check a property.

More comparison points are monument protection by state, permit-free building by state and road development contributions by state.

What the map does not prove

A map shows a data representation at a particular time. It proves no ownership, secured access, servicing or building eligibility. Property-law review also requires the land register, public-law building obligations, contracts and notices. § 2 GBO treats the Grundbuch as a register, while § 13 GBO concerns an application for entry.

Sources and review date

The planning-law provisions are § 10 BauGB, § 30 BauGB, § 34 BauGB, § 35 BauGB, § 196 BauGB and § 199 BauGB. The Bundesministerium für Wohnen explains the federal framework; state entry points appear in the table.

For land-register questions, see § 2 GBO, § 12 GBO and § 13 GBO. Stand: August 2026. This is general information and does not replace information from the survey office, municipality or valuation committee. Further reading: land register and ALKIS, zoning and buildability, monument protection by state, permit-free building by state and road development contributions by state.