SaaS Rails Kit

The SaaS Rails Kit gets your new software-as-a-service site off to a running start by providing you a well-tested and proven recurring billing system with credit card and PayPal payments. You also get a framework for building membership-based applications, including account signups/upgrades/downgrades, tiered pricing levels with customizable limits (e.g, # of users, # of projects, etc.), multi-tenant data security in a single database, and more.