The biographical and historical details from the Hymns Old and New website for the 1987 edition are available on a free app at
From the ‘Hymn Index’ tab, you can scroll to any hymn or enter the number in the search box and jump to it.
Selecting a hymn will open full details for that hymn, and you can jump from there to the full author details.
Similarly, from the ‘Authors’ tab, you can scroll or use search to jump to an author.
Selecting a single author will display full details, including each of their hymns. You can select any of the author’s hymns to jump to it.