[stickfigure]

We wrote our own, but that's because of the nature of our business and our program. YMMV.

If you're trying to get professional affiliates to market your business, sure, use third party software. Most the affiliates know the systems already and have some level of trust in it. Plus the software will provide analytics, payouts to various countries, tax guidance, etc.

Our program is primarily a referral program for existing customers. There's no separate affiliate account and credits automatically offset the fees we charge. Plus I like Stripe and don't want a bunch of third-party PHP crapware invading our already complex billing system. DIY was really the only option.

The things that make our customers want to refer others are not necessarily what will work for anyone else. Our current referral system would never fly with the porn affiliates, but also an impersonal "make $ fast!" affiliate system would never resonate with our customers.

A basic referral tracking system is super easy. Give users links they can share; clicking on the link puts a value in local storage; pass that value along with signups. Offer something meaningful to new customers who come in through a referral (for us, it's a discounted first month). If you're just trying to increase word of mouth spread, that's enough to get started.