|Reference code for a Mapillary image|
|Used on these elements|
|Status: in use|
|Tools for this tag|
This key describes a reference code to an image in Mapillary, the Facebook-owned street-level imagery platform. This image should be representative of the object, and could be used in a map popup or similar. It could also just be used as an alternative to Key:source, making it easier for experienced armchair mappers to validate edits to details which might otherwise be hard to find info on. If there are multiple images, the "best" image should be prioritized.
This key uses the unique key Mapillary assigns to each photo, not a direct link. The reason for adding the key and not the full URI is that the URI might change (and already did in the past), but the key will stay the same. For the same reason the direct link to the image (e.g. https://images.mapillary.com/.../thumb-2048.jpg) should not be tagged. To retrieve this key, open the Image details (⋯) menu and click Advanced options. Then copy the image key. For example, the tag mapillary=US-sClDbAWhtGYc-d3L4nw references the image in https://www.mapillary.com/map/im/US-sClDbAWhtGYc-d3L4nw.
The JOSM Mapillary plugin allows adding this tag with just 1 click.
The object itself can also be tagged in the Mapillary picture, according to the Mapillary tag list.
If the intention is simply to point to Mapillary as the source of data for the OSM object, it's enough to add source=mapillary in the object or changeset.
Origin of this tag: 
- OpenLevelUp displays Mapillary pictures associated to indoor objects, and supports mapillary=* and mapillary:*=* tags.
- Overpass Turbo also uses the Mapillary tag.
- JOSM can open a browser with the specific image linked (select the mapillary tag, then right-click). Very usefull when there are hundreds of images in a small area and only 1 or 2 shows the object satisfactorily.
- MapComplete displays Mapillary pictures.