Odoo is an all-in-one management software that offers a range of business applications that form a complete suite of enterprise management applications.

InvoiceBerry offers online invoicing & expense tracking for small businesses, freelancers and sole traders.

TimeCamp is an advanced time-tracking app which also offers a variety of reporting, billing, and invoicing features.

InvoicePlane is a self-hosted open source application for managing your quotes, invoices, clients and payments.

Nukern is a billing software in the cloud, specialized for web hosting companies. It automates the recurring invoices and the entire life cycle of web hosting…

Vosae is an invoicing, organizer, contacts app.