Square is a well-known payment processor widely used by small businesses. Why, then, does OwnerRez not support Square?
The problem is that, unfortunately, Square does not allow processing card numbers we pass them. In other words, they have no API software connection that OwnerRez can use to pass the credit card data into Square's system.
Instead, the guest has to enter the number in one of their forms to get the card processed. This is kind of like how PayPal works - if you've used PayPal to make online payments, you've noticed that the process moves you off of the site you're buying from, and into PayPal's site instead. This is also part of why we don't recommend PayPal as a primary payment method.
Many channel API integrations such as HomeAway and Booking.com pass the card numbers to us securely, and then we process them using your processor. We also have areas where you can key in a card number over the phone and process the card directly.
Since Square doesn't work at all for either of those scenarios, it could only ever be a partial solution for OwnerRez users - you'd still need to have a normal card processor to meet all your needs. Therefore, Square has become a bit lower on the priority list than other integrations.
Every other card processor we support does allow processing card numbers, and the entire system is built around that concept. To support redirecting guests to Square's entry forms and remove any owner key in of cards would be quite a large undertaking!
If Square ever supports direct card processing, we'll add support for them, but that's the state of things as of now.
In the meantime, if you want to use Square, you could go to Settings > Payment Methods and add a Custom Instructions payment method. That technique allows you to give instructions to the guest for how to pay after booking -- so you can tell them you'll send them an invoice via Square, Venmo, Zelle, etc. Once they have paid, go into the booking in OwnerRez and record the payment.