Maidenhead Locator API
Convert between latitude/longitude and the Maidenhead Locator System — the grid-square "QTH locator" (like JN58td or IO91wm) used by amateur radio, APRS and contesting to describe a position compactly. The encode endpoint turns a latitude and longitude into a locator at 4-, 6-, 8- or 10-character precision. The decode endpoint turns a locator back into the centre coordinates, the south-west corner and the size of the grid square. The distance endpoint gives the great-circle distance (kilometres and miles) and bearing between the centres of two locators — the classic "how far and which way is that station". Everything is computed locally and deterministically, so it is instant and private. Ideal for amateur-radio and APRS tools, contest logging, antenna aiming, and grid-based mapping. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is the Maidenhead system; for Plus Codes, MGRS, UTM and DMS use a geo-convert API and for precise geodesic distance use a geodesy API.
api.oanor.com/maidenhead-api
