CertSimple only does EV, and we do it completely differently from every other company: we check as much of your company's details before you pay, matching your order to a registered/active entity, flagging up things before asking for your credit card number, and helping you resolve any missing identification steps based on your company, order and the domain names involved.
I've been on HN for a decade and was at YC in Mountain View last week for the 10-min final interview last week (we didn't make it, which I blame on me being a jetlagged mess). OTOH the AirBnB we stayed in used a customer as their ISP.
We're used by a bunch of companies HN folks might know, including Travis, Tito, and Monzo.
Also, inventory management, which is helpful when you have hundreds or thousands of certs.