Sentinel-2

Sentinel-2 is an ESA programme of earth observation satellites. Among others, it provides worldwide 10 m resolution colour imagery.

The resolution is higher than Landsat, but lower than Bing, Mapbox etc.

Example of a single tile

Licence

EU law grants free access to Copernicus Sentinel Data and Service Information for the purpose of the following use in so far as it is lawful:

Worldwide coverage in 10 m resolution and full colour
Very recent, imagery updated between every month to every two weeks and available just a few days after sensing date

Published data needs to be processed into usable background imagery by the end user
Tiles may be cloud covered, check the thumbnails before processing
Resolution only sufficient to trace major roads and landuse features.

For the most recent imagery, but with a monthly limit: Using a Copernicus WMS/WMTS Link. You need to sign up for free and then create an "instance" using the "configuration utility" from the Sentinel Hub Dashboard. This blogpost may help with the setup. (Note that while there are many customization options, if you just want the standard imagery, you can select the TRUE_COLOR base product from the dropdown list for the "data processing" field when creating a layer) Once set up, you can then call your personalized configuration as WMTS (or WMS) services using your generated Instance ID and Layer ID. Tip: Check your usage in the dashboard, the monthly limit is not very high, you might want to use this imagery sparingly. You can tweak the URLs below which contain the parameter "REQUEST=GetTile" by adding additional parameters like maximum acceptable cloud cover.

For the EOX cloudless Sentinel-2 layer
- In JOSM: Activate directly from Preferences -> Imagery
- in iD (and others):
  - WMS (2023) – https://tiles.maps.eox.at/?FORMAT=image/png&TRANSPARENT=TRUE&VERSION=1.1.1&SERVICE=WMS&REQUEST=GetMap&LAYERS=s2cloudless-2023_3857&STYLES=&SRS={proj}&WIDTH={width}&HEIGHT={height}&BBOX={bbox}
    You can replace 2023 by any year starting from 2018 to get those year's images.
  - WMTS (2023) – https://tiles.maps.eox.at/wmts/1.0.0/s2cloudless-2023_3857/default/g/{z}/{y}/{x}.jpg (Direct link to stand-alone iD version)
    You can replace 2023 by any year starting from 2018 to get those year's images.
See also the WMTS and WMS links on https://s2maps.eu/ for possibly more recent cloudless versions and other mosaic endpoints (do note that the licensing of the other mosaics is disputed and may be technically/legally unfit for tracing).
Please note that "Attribution as described at https://s2maps.eu/#license must be provided in a suitable OpenStreetMap changeset tag"^[1], eg the source tag.
Manual solutions : If you need the maximum possible resolution or recent imagery, you can download unprocessed data directly from ESA and convert it to a background layer. See User:Ff5722/Using Sentinel-2 imagery and TrickyFoxy's diary: Fresh Sentinel-2 in your editors. With QGIS, but easier (easier addendum to the above manual).
A plugin to use Sentinel Hub backgrounds directly with JOSM has been proposed back in 2017, see ticket #14921

A changeset tag of source=Sentinel-2 should be used. This is the most common Sentinel source value used per taginfo.