We've been getting a lot of requests for a referral/affiliate program. After looking at a few options, Affonso (https://affonso.io) seems like the best fit since it's built specifically for SaaS. It integrates with all major payment processors and handles payouts to affiliates for us — no need to deal with invoices, currencies or tax stuff manually. They also have an affiliate finder that helps you discover partners in your niche, plus a marketplace where affiliates can find your program. Setup looks pretty straightforward, should only take a few minutes to get running.