not really niche yet but good starting point to branch off to niche tools!
You should definitely consider adding save to / load from localStorage, IndexedDB, or URL.
Nice thing about URL is you can send pages to other people like this:
https://unli.xyz/tabsender/?links=%22open%20a%20bank%20accou...
Or use LZString https://github.com/pieroxy/lz-string like this:
https://unli.xyz/html/edit.html?t=%22DwBwfALghgTgXlAdsA9OYAz...
An accidental page refresh shouldn't eliminate all your TODOs :/