Shoot out to api to check something after submit button

Hi, we are wanting to use a bank account validation method via api after taking the details into a customer form and submitting, so it can be checked directly after input. 

Can anyone let me know if this may be possible on a knack from? (we have access to the checker which has a standard api format available).

Thanks.

Andrew (UK)

I do this using JavaScript and usually on the on record create, then call the API you want to.