Steve Roud's Folk Song Index, available at the Vaughan Williams Memorial Library, is the other major song catalog on the Internet, and the Ballad Index cites Roud numbers.
Jane Keefer's Folk Music - An Index to Recorded Resources includes an extensive collection of recordings, both from traditional singers and modern pop performers.
Hymnary.org, source notes, author notes, versions of hymns and religious songs (mostly American). Not all the source information is accurate, but it is usually much better than individual hymnals.
John Baxter's Folk Song and Music Hall has texts and detailed information about hundreds of songs with links to the music hall and which also connect with oral tradition.
Mainly Norfolk has information about English "folk" music and performers.
You can find broadside prints at the following sites (among others):
The Ballad Index is copyright © 2025 by Robert B. Waltz and David G. Engle.