Sources and licenses

The images are free to use but usually require credit. This is my understanding, not legal advice. Check the terms yourself, especially for commercial use and before passing tiles on.

Region	Service	Layer	Credit
Thuringia, Germany	WMS	th_dop	© GDI-Th, CC BY 4.0
Lower Saxony, Germany	WMS	ni_dop20	LGLN, CC BY 4.0
North Rhine-Westphalia, Germany	WMS	nw_dop_rgb	Geobasis NRW
Saxony-Anhalt, Germany	WMS	lsa_lvermgeo_dop20_2	© GeoBasis-DE / LVermGeo ST, dl-de/by-2-0
Saxony, Germany	WMS	sn_dop_020	Geodaten Sachsen (GeoSN), dl-de/by-2-0
Brandenburg, Germany	WMS	bebb_dop20c	© GeoBasis-DE/LGB, dl-de/by-2-0 (data modified)
Hesse, Germany	WMS	he_dop_rgb	Hessische Verwaltung für Bodenmanagement und Geoinformation
Rhineland-Palatinate, Germany	WMS	rp_dop20	©GeoBasis-DE / LVermGeoRP (Jahr), dl-de/by-2-0, [Daten bearbeitet]
Saarland, Germany	WMS	sl_dop20_rgb	Geoportal Saarland
France	WMS	HR.ORTHOIMAGERY.ORTHOPHOTOS	BD ORTHO®, IGN, Licence Ouverte 2.0
Poland	WMS	Raster	Główny Urząd Geodezji i Kartografii
USA	WMS	USGSNAIPPlus	USDA NAIP über USGS The National Map
Worldwide, 10 m	WMS	s2cloudless	EOxCloudless by EOX IT Services GmbH (Contains modified Copernicus Sentinel data 2016 & 2017), CC BY 4.0

NASA

Content	Source
Day	Blue Marble Next Generation, October 2004, without relief
Night	Black Marble 2016
Clouds	Blue Marble Clouds

Credit: NASA Earth Observatory.

Deliberately not used

Esri, Google and Bing: their terms don’t fit mass downloads and videos. EOX vintages from 2018 on: non-commercial only.

FlightGear

FlightGear is licensed under the GPL. Changed FlightGear files such as the water fixes remain under its license.