Landscaping CRM but I can use my own payment processor?

Hi, I am looking into all different softwares (mostly just the ones advertised as CRMs for now) for my new landscaping company. I was in the process of taking over another kind of business but that fell through, but during that set-up, I got an account with Helcim and even got one of their terminals. I am hoping to use Helcim's API payment processor with my new CRM. Its just me running this business, I don't need anything too fancy. Anyone know of a platform that can do this? Thanks