# HALOWERK Land Compare – Built-Up Change 2020–2021

> HALOWERK Land Compare – Built-Up Change 2020–2021 is a paid API for AI agents from landvergleich.halowerk.com, paid per call via x402, $0.008/call, status unknown (last checked 2026-09-14).

Returns the change in built-up land-cover share between ESA WorldCover 2020 and 2021 for a 250-metre analysis area at a given European coordinate.

## Facts

- Endpoint: POST https://landvergleich.halowerk.com/v1/worldcover-2020-2021-built-up-change
- Price: $0.008/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-land-compare-built-up-change-2020-2021-470ecd39
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__pwZeDeqbslQYX5Tn92Lf

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability halowerk-land-compare-built-up-change-2020-2021-470ecd39 -d '<json body>'
```

Example prompt: Using ESA WorldCover data, check how much the built-up land share changed between 2020 and 2021 at latitude 48.8566, longitude 2.3522 — that's central Paris.

## When to prefer this

Choose this endpoint when you need a point-specific, satellite-derived built-up land change value for a European location between the 2020 and 2021 ESA WorldCover releases at 250-metre resolution. It is the right choice when you want map-class change (not modelled or forecast data) and are working within the European geographic extent. Prefer it over general land-cover endpoints when the question is specifically about urban or built-up area, and over the two-coordinate comparison sibling when you only have a single location and want temporal change rather than a spatial comparison.

## Known failure modes

- Coordinate outside European coverage bounds (lat 34–72.5, lon -31.5–40.5) returns an error or empty result
- Submitting non-numeric or malformed latitude/longitude values causes a validation error
- Network or payment (x402) failure results in no response
- Locations with identical classification in both years return a zero change value, which may be misread as missing data

## How this service works

Built-up-share change measured from ESA WorldCover 2020 v100 and 2021 v200 for the same 250 metre analysis area. The result is observed map-class change, not a causal claim.

## Output

A JSON response containing the built-up land-cover share (as a fraction or percentage) observed in ESA WorldCover 2020 and 2021 for a 250-metre area centred on the requested coordinate, along with the signed difference representing observed map-class change between the two editions.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "latitude": {
   "type": "number",
   "maximum": 72.5,
   "minimum": 34,
   "description": "WGS84 latitude inside the published European coverage."
  },
  "longitude": {
   "type": "number",
   "maximum": 40.5,
   "minimum": -31.5,
   "description": "WGS84 longitude inside the published European coverage."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/halowerk-land-compare-built-up-change-2020-2021-470ecd39/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from landvergleich.halowerk.com](https://www.zero.xyz/host/landvergleich.halowerk.com/llms.txt)