Transaction Listener

I’m hoping to find an API that supports supplying a rule (ie regex on note field, or ASA-type) to receive a notification when a transaction occurs matching that criteria.

Anybody know of any packages that support this? The only option I’ve discovered is to do periodic lookups via the Indexer, but that’s not ideal for my use case.

If this ? is better suited for a different forum, plz point me to that. Thank you!