Interesting. One of our customers just requested this today, where they want to test form fields. Are you imagining higher form submission conversions by optimizing the number, type, and layout of the fields?

Yes ideally closing the loop on the value of those conversions as well

The pitch would be “automatic ab testing for your form submissions”. I talked to a few local lead gen companies years back and they thought it was a neat idea, I just never got around to building it.

A quick google search gives me several tools for this : Formstack, Omnisend, Zuko Form Analytics...

AFAICT Formstack and Omnisend are marketing automation and analytics services, not automatic split testing. I got out of the marketing space a while back but I do appreciate the cross check! However it doesn't look like those products are doing exactly this.

+1 that's my understanding as well.

I also think this could be a really cool chance to use the 1 arm bandit optimization algorithm, as it self-corrects so users don't even need data readouts.