Garmin GPI (Points of Interest)

GPI is the container for custom points of interest on Garmin devices. Lists of cafes, fuel stations, parking or service objects are packed into it, and the navigator shows them on top of the stock map. The format is proprietary and has never been publicly documented.

That closedness is what decides how the file is built. There is only one practical benchmark of correctness — the writer from GPSBabel, recovered by reverse engineering; home-made byte writing diverges from it in the header, the nested records and the terminators, and devices reject such files. So we do not write the container ourselves: the points of your area go out as GPX, and that reference tool turns them into the .gpi.

The file carries the point features of the chosen area with their OpenStreetMap name and category: cafes, shops, pharmacies, fuel, parking, attractions. Lines and outlines are not stored — .gpi is a points format, not a map.

Names survive the trip. There is no Unicode inside a .gpi: strings are written in a single-byte code page, and a hard-coded choice would silently turn "Аптека" or "Café" into question marks. We pick the code page that fits the content of your area, and fall back to UTF-8 when one page is not enough. And there will be no empty file: if the area holds no points we say so plainly instead of handing you a technically valid .gpi that shows up as an empty list on the device.