How to add missing album covers to your songs
Songs without a cover show an empty square in most players. 432 Librarian finds covers and saves them into the files.
Before you start
Chrome or Edge on a computer, to save into the files. HD covers (1200 px) need a free account; a guest gets the standard size. Each song saved counts as a fix.
Steps
Choose your music folder
Open the app, go to the Health tab and tap Choose folders. On a first visit the welcome asks for it. Pick the folder where your music is, and allow the browser to change it if it asks.
See which songs have no cover
On the Health tab, tap No album art to see those songs in the Library.
Find covers
Tap Find fixes, then Find fixes on the Fix and fill page. A cover found for a song shows as Album art, with the picture and its source.
Tick and save
Tick the covers that match the album, untick the others, and tap Save N changes into the files. The cover goes into each song file, with a backup and Undo.
Or pick one cover by hand
In the Library, open a song. Under its cover at the top, tap Find online and tap one of the covers found, or tap Choose from device to use your own picture. Then tap Save.