The size of the library is only a part of the data that could be used by the application. The app itself is about 50 MB which may be included in what is displayed. There are some cache files that are created and retained but they are usually small. There is also iTunes File Sharing which is a location within the app where files can be transferred back and forth between the app and iTunes. This is most likely what is taking up space.
Go into the Songs menu and choose the All Songs tab. Tap on the + button and then choose Import > iTunes File Sharing. See if there are files in there that you no longer need. You can then swipe right to left over each file that you don't want and tap on the Delete button to remove the file. This is used as a location to import and export files to and from your OnSong library.
If this area contains backup files, you will also want to check your backup settings. Go into the Utilities menu (gear icon) and choose Backup. Make sure that the "Append a timestamp to the filename" option is disabled. If not, every time that OnSong creates a backup file it will great a new file. You will also want to choose Dropbox as the backup location so the backup file is sure to be stored off of the device: http://onsongapp.com/docs/interface/menubar/utilities-menu/backup/
Hope that helps!
Related Articles
How much space do I need for my OnSong library?
OnSong is designed to store content you import on you device. This allows OnSong to work in live scenarios when an Internet connection may not be present. Most of the time these files take up very little space. OnSong works best with text-based chord ...
How do I backup my work in OnSong?
Thanks for using OnSong! Backing up your library is a great way of keeping your hard work safe. Bad things happen and your iPad may get lost, stolen or just plain stop working. Here's a video tutorial that guides you through backing up to Dropbox and ...
Can I import/export files to an external drive?
With iOS/iPadOS 13, Apple has made the Files app even more powerful. Now you can not only access your iCloud contents and storage providers like Dropbox, Microsoft OneDrive and more, you can also attach and access files on connected external drives. ...
How do I restore a backup?
To restore a backup, it essentially just depends on what source you used to backup your library initially. If you backed up to Dropbox, go into Songs --> All Songs and tap on the "+" button as if you were importing songs. Tap on Dropbox and sign in. ...
How do I make OnSong automatically backup my library?
To enable automatic backups, you can set this up for OnSong by opening the Utilities Menu by tapping on the gear icon in the Menubar and choosing Backup. This will open the Backup Screen where you can configure OnSong for automatic backup. Export ...