Offering customizable user interfaces and secure payments with one-off or subscription payments through a recurring billing platform, FastSpring is a great solution. The downside is that the focus is entirely on software (Mac software publishers in particular) so unless you are in that market, its usefulness may be limited.
However, the pricing structure is based on a small transaction fee plus a percentage, which makes it ideal for business of any size. You won’t be paying for a service that doesn’t get used, and the final fees are proportionate to your sales.
ChargeBee is a recurring billing software that is built as subscription management software – it’s not a feature that’s added on top. Plenty of automation is included as is a CRM system, helping businesses in multiple ways.