The Dexie userID is case sensitive. Which is fair enough, but it's used for email addresses, which aren't.

So [email protected] and [email protected] or any number of different combinations will all work for a user signing in, especially one on a mobile phone where auto-capitalization is not unknown. The result, is multiple independent accounts, all for a single email address (because they are one address: capitalization is ignore in email).

That's not exactly a defect, but if you end up with multiple different accounts all for a single user, you're going to have a nightmare of a manual merge operation on your hands before you're done.

My suggestions would be:

• Anyone writing their own UI should lowercase all email stuff on the input side, so there's no risk of alternative casings getting into the wild.
• Dexie, should probably not treat the same email address as different based on case alone, or could support some option which lowercases everything on input to avoid the mess.