I added this code just before the end of the script to add a button to download a ".txt" file of the export list for easy backup :)

function exportToTxt() {

var kudos_history = {
kudosed: { list: localStorage.getItem('kudoshistory_kudosed') || ',' },
seen: { list: localStorage.getItem('kudoshistory_seen') || ',' },
bookmarked: { list: localStorage.getItem('kudoshistory_bookmarked') || ',' },
skipped: { list: localStorage.getItem('kudoshistory_skipped') || ',' },
checked: { list: localStorage.getItem('kudoshistory_checked') || ',' }
};

var export_lists = {
kudosed: kudos_history.kudosed.list,
seen: kudos_history.seen.list,
bookmarked: kudos_history.bookmarked.list,
skipped: kudos_history.skipped.list,
checked: kudos_history.checked.list
};

var textToSave = JSON.stringify(export_lists, null, 2);
var blob = new Blob([textToSave], { type: "text/plain" });
var a = document.createElement("a");
a.href = URL.createObjectURL(blob);
a.download = "AO3_history.txt";
document.body.appendChild(a);
a.click();
document.body.removeChild(a);
}

$(document).ready(function () {
var menu = $('

');
var menuList = $('

');
menuList.append($('

').append($('Export to .txt').click(exportToTxt)));
menu.append(menuList);
$('ul.primary.navigation.actions').append(menu);
});

Ahh bless you for this! Thank you! Is there a way to make it so you can also import the text file rather than having to copy/paste into the box? My list has gotten so long that it gets cut off when I try to paste it into the box 😭

Thank a lot for that snippet! I used it to make a script that adds-on Export & Import buttons. You can find the script on my page if you're interested.

Some people asked me to make a separate script, so I added the import button (Thanks C89sd for the idea!, my turn to use your snippet) and changed the menu name

https://greasyfork.org/pt-BR/scripts/529837-backup-menu-ao3-kudosed-and-seen-history