Filter known breaches and pastes in the API
It would be nice if we could pass a set of breach names into the https://haveibeenpwned.com/api/v3/breachedaccount and a set of paste data into https://haveibeenpwned.com/api/v3/pasteaccount and have them only provide results for the breaches and pastes not on the list, basically something like ?exclude=thing1,thing%20two for breachedaccount and something like ?exclude=%7B%22PasteBin%22:%20[%22123%22,%22456%22],%22Pastie%22:%20[%22abc%22]%7D for pasteaccount.
That sounds like something you could easily filter on the client end: request the data for an account then remove all items that don’t match what you’re looking for. There’d be no performance benefit doing it on the HIBP end as the query presently just picks up an entity (the account being searched for) and returns it in its entirety.