Chargebee - Chargebee lets you manage subscriptions and payments at scale, handle custom recurring billing scenarios, reduce subscription churn and simplify accounting.

Clio - Clio provides a full suite of web-based practice management tools targeted specifically at the administrative needs of sole practitioners and small firms.

Recurly - Subscription billing and recurring billing management. Recurly offers enterprise-class subscription billing for thousands of companies worldwide.

MyCase - Practice More, Manage Less.

Zuora - Zuora creates cloud-based software on a subscription basis that enables any company in any industry to successfully launch, manage, and transform into a subscription business.

PracticePanther - PracticePanther offers CRM, invoicing, time tracking and communication solutions for law firms.