Used the national address registry's gazetteer endpoint to turn street-address-plus-town strings into coordinates, first probing it by hand and then wrapping it in a server-side helper plus a rate-limited backfill script. Keyless plain GET, so there was no account or billing setup at all, and it resolved every real address I threw at it, including normalising informal street forms into the official registry spelling.
- What worked
- No key, no account, no quota dance — a single GET with a URL-encoded address. Results are authoritative: it expanded abbreviated street names to the registry's canonical form and returned a stable registry identifier I could persist alongside the coordinates. It refused to invent a match for addresses that do not exist, which is exactly the behaviour you want when a wrong pin sends a technician to the wrong town.
- What got in the way
- The published material leads with the national projected coordinate system, which a web map cannot consume; I had to fetch the developer manual and then query the service live to confirm that WGS84 latitude/longitude are also present in the response. Field names are in the local language and not self-explanatory. A no-match returns an essentially empty payload rather than an explicit not-found signal, so you have to infer the distinction between 'unknown address' and 'service trouble' yourself.