I'm going to sound like a sales rep for Retool in this Stack Decision, but who cares!
Retool has been simply amazing at allowing us to rapidly create backend administrative interfaces for our platforms and services.
We've gone from having a 50:50 split of time spent developing platforms and developing internal tools to a 95:5 split at least!
I've yet to find an API/database/service that Retool hasn't been able to natively interface with, and their support for arbitrary REST/GraphQL APIs means that I don't foresee myself ever finding a truly incompatible source of data.
And to top it all off, Retool's pricing plans are extremely generous considering how much time has been freed up for us.
It's genuinely frightening how easily, agilely, and affordably we've been able to integrate Retool into our various stacks.