Zendesk - Zendesk is a beautiful, lightweight help-desk solution.
Service Provider Pro - Client Portal Software. Productize your services and turn your agency into a profitable and scalable system.
Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community
Client Portal - A client-friendly way to keep your projects organised
HelpScout - Help Scout is a simple, straightforward way to provide excellent support
Function Point - Function Point is project management software tailored to the unique and specific demands of creative professionals.