Bronwijzer›For AI

Built to be found, by AI too

People increasingly ask an AI assistant where to find figures. Bronwijzer gives that assistant a reliable answer: which source, how current, what you can do with it and what to watch out for. Everything below comes from the same YAML files as the site, and the links work.

llms.txt

/llms.txt

# Bronwijzer

> Index of open data about the Netherlands, and international sources covering it. Per source: contents, uses, processing steps, combinations, caveats, access and status.

## Sources
- [Amsterdam grants register](http://localhost:3471/en/bron/ams-subsidies.md): Gemeente Amsterdam · grant file · daily · Open
- [Population change by month](http://localhost:3471/en/bron/cbs-bevolking-maand.md): CBS · municipality · monthly · Open
- [Key figures for districts and neighbourhoods](http://localhost:3471/en/bron/cbs-kwb.md): CBS · neighbourhood · yearly · Open
- [Copernicus Sentinel-2](http://localhost:3471/en/bron/copernicus-sentinel2.md): ESA en Europese Commissie · 10 metres · daily · Account
- [data.overheid.nl](http://localhost:3471/en/bron/data-overheid.md): Ministerie van BZK · varies · daily · Open
- [EEA air quality](http://localhost:3471/en/bron/eea-lucht.md): Europees Milieuagentschap · monitoring station · daily · Open
- [ERA5 climate reanalysis](http://localhost:3471/en/bron/era5.md): Copernicus (ECMWF) · approx. 30 km · daily · Account
- [ESA WorldCover](http://localhost:3471/en/bron/esa-worldcover.md): ESA · 10 metres · complete · Open
- [Eurostat](http://localhost:3471/en/bron/eurostat.md): Europese Commissie · region (NUTS 3) · monthly · Open
- [GBIF biodiversity](http://localhost:3471/en/bron/gbif.md): Global Biodiversity Information Facility · observation · daily · Open
- [KNMI daily weather data](http://localhost:3471/en/bron/knmi-daggegevens.md): KNMI · weather station · daily · Open
- [Chamber of Commerce business register](http://localhost:3471/en/bron/kvk-handelsregister.md): Kamer van Koophandel · company · daily · Paid
- [Luchtmeetnet air quality network](http://localhost:3471/en/bron/luchtmeetnet.md): RIVM, GGD's en provincies · monitoring station · hourly · Open
- [NASA FIRMS (fires)](http://localhost:3471/en/bron/nasa-firms.md): NASA · 375 metres · hourly · Free key
- [NASA GIBS and Worldview](http://localhost:3471/en/bron/nasa-gibs.md): NASA · 250 – 750 metres · daily · Open
- [NDW live traffic data](http://localhost:3471/en/bron/ndw-verkeer.md): Nationaal Dataportaal Wegverkeer · road sensor · every minute · Open
- [NS travel information](http://localhost:3471/en/bron/ns-reisinformatie.md): NS · station and trip · every minute · Free key
- [open.overheid.nl (FOI documents)](http://localhost:3471/en/bron/open-overheid-woo.md): KOOP · document · daily · Open
- [Open Council Information](http://localhost:3471/en/bron/openraadsinformatie.md): Open State Foundation en VNG · municipality · daily · Open
- [OpenSky Network](http://localhost:3471/en/bron/opensky.md): OpenSky Network · aircraft · every minute · Open
- [OpenStreetMap](http://localhost:3471/en/bron/openstreetmap.md): OpenStreetMap Foundation · feature · every minute · Open
- [Addresses and Buildings Register (BAG)](http://localhost:3471/en/bron/pdok-bag.md): Kadaster, via PDOK · address and building · daily · Open
- [District and neighbourhood map](http://localhost:3471/en/bron/pdok-wijkenbuurten.md): CBS en Kadaster, via PDOK · neighbourhood · yearly · Open
- [Registered crime by neighbourhood](http://localhost:3471/en/bron/politie-misdrijven.md): Politie, via CBS · neighbourhood · monthly · Open
- [Registered nuisance by neighbourhood](http://localhost:3471/en/bron/politie-overlast.md): Politie, via CBS · neighbourhood · monthly · Open
- [RDW registered vehicles](http://localhost:3471/en/bron/rdw-voertuigen.md): RDW · licence plate · daily · Open
- [Large-scale concentration maps (GCN)](http://localhost:3471/en/bron/rivm-gcn.md): RIVM · 1 × 1 km · yearly · Open
- [World Bank indicators](http://localhost:3471/en/bron/worldbank.md): Wereldbank · country · quarterly · Open

## Questions
- Is there more nuisance in my neighbourhood than last year?: politie-overlast, cbs-kwb, pdok-wijkenbuurten
- How much grant money does a foundation in Amsterdam receive?: ams-subsidies, kvk-handelsregister, openraadsinformatie
- How much warmer has it become?: knmi-daggegevens, era5
- How clean is the air on my street?: luchtmeetnet, rivm-gcn, eea-lucht
- What does my area look like from space?: copernicus-sentinel2, nasa-gibs, esa-worldcover
- Did house prices rise faster here than elsewhere in Europe?: eurostat, cbs-kwb
- How many cars in my municipality are electric?: cbs-kwb, rdw-voertuigen

## API
- [Catalogue as JSON](http://localhost:3471/api/bronnen)
- [Search 20,000+ datasets](http://localhost:3471/api/zoek?q=lucht)

Every source page also as Markdown

/en/bron/knmi-daggegevens.md

# KNMI daily weather data

Daily values from over fifty weather stations: temperature, rainfall, sunshine and wind. The De Bilt series starts in 1901.

- Publisher: Koninklijk Nederlands Meteorologisch Instituut
- Area: Netherlands · Finest detail: weather station
- Period: 1901 – 2026 · Refreshed: daily
- Access: Open · Licence: CC BY 4.0
- Join keys: stationsnummer, datum
- Status: bad
- URL: https://www.knmi.nl/nederland-nu/klimatologie/daggegevens

## What can you do with it?
- **Was this summer exceptional?.** Compare this summer's mean with all summers since 1901 and see where it ranks.
- **Count the tropical days.** A tropical day has a maximum of 30 °C or more (variable TX). Count them per year.
- **Build your own warming stripes.** One stripe per year, coloured by deviation from 1901–1930. The chart on this page is exactly that.

## How to process it
1. **Choose station and variables.** De Bilt is 260. Variables: TG (mean), TX (max), TN (min), RH (rain), SQ (sunshine).
2. **Fetch daily values.** One POST request with start and end date. JSON is easiest.
   `curl -d "stns=260&vars=TG:TX&start=19010101&end=20251231&fmt=json" https://www.daggegevens.knmi.nl/klimatologie/daggegevens`
3. **Divide by ten.** Temperature and rain are in tenths. -1 for rain means less than 0.05 mm.
4. **Average per year or season.** Drop or flag years with missing days, or the average will be skewed.

## Interesting combinations
- More nuisance in warm weather? → [politie-overlast](http://localhost:3471/en/bron/politie-overlast.md) via datum (maand). Compare monthly temperature with reports and with the same month in cooler years.
- Is air worse in still weather? → [luchtmeetnet](http://localhost:3471/en/bron/luchtmeetnet.md) via datum en uur. Wind (FG) and hourly air quality together show how much the weather determines.

## Similar sources
- [era5](http://localhost:3471/en/bron/era5.md): A grid over all of Europe, including where no station stands, but coarser.
- [KNMI Data Platform](https://dataplatform.knmi.nl): Hourly data, radar and models. Requires a free API key.

## What to watch out for
- **Raw measurements, not a trend series.** Changes in instruments and surroundings are part of this series. KNMI also publishes a homogenised De Bilt series; use that when comparing periods before 1951.
- **One station is not the whole country.** On the coast summers are cooler and winters milder than in De Bilt. Pick the station that fits your question.
- **Values in tenths.** TG = 115 means 11.5 °C. Rainfall is in tenths of a millimetre.
- **Recent days are provisional.** The most recent days may still be corrected after validation.

## How to fetch it
```bash
curl -d "stns=260&vars=TG&start=20250101&end=20251231&fmt=json" \
  https://www.daggegevens.knmi.nl/klimatologie/daggegevens
```

APIs

MCP server (planned)

The same functions as the API, so Claude, ChatGPT and other assistants can search the index directly.

{
  "tool": "zoek_bron",
  "input": {
    "vraag": "air quality",
    "gebied": "Amsterdam"
  },
  "output": [
    {
      "id": "luchtmeetnet",
      "naam": "Luchtmeetnet air quality network",
      "pagina": "http://localhost:3471/en/bron/luchtmeetnet.md"
    },
    {
      "id": "rivm-gcn",
      "naam": "Large-scale concentration maps (GCN)",
      "pagina": "http://localhost:3471/en/bron/rivm-gcn.md"
    },
    {
      "id": "eea-lucht",
      "naam": "EEA air quality",
      "pagina": "http://localhost:3471/en/bron/eea-lucht.md"
    }
  ]
}