See green text in bottom-right at https://www.openstreetmap.org/ https://www.openstreetmap.org/ linking to https://donate.openstreetmap.org/ https://donate.open

See green text in bottom-right at https://www.openstreetmap.org/ https://www.openstreetmap.org/ linking to https://donate.openstreetmap.org/ https://donate.openstreetmap.org/ There are also popups during part of the year, but someone with axe to grind ensured that they were added to the adblock filter lists.