We've been very happy with Clearout's API and easy integration into our forms. Their pre-paid, pay-as-you-go pricing is fair and much more cost-efficient than monthly subscriptions, which seem to be most common in the industry. There was a substantial savings switching to Clearout from BriteVerify, our previous source and more features. I haven't needed any support in the 1.5 years I've been using Clearout, but I feel like it's good and right there if I need it.