Joist - Joist is a mobile application to manage estimates, invoicing and accounting for contractors.
Invoice Ninja - Invoice Ninja is a free, open-source solution for invoicing and billing customers.
Invoice Genius - Invoice Genius is a FREE invoice maker app for freelancers, contractors, and small businesses that...
Harvest - Simple time tracking, fast online invoicing, and powerful reporting software. Simplify employee timesheets and billing. Get started for free.
FieldPulse - All-in-one field service management solution
GnuCash - A personal and small-business financial-accounting software, licensed under GNU/GPL and available for Linux, Windows, Mac OS X, BSD, and Solaris.