User-friendly, powerful and feature rich accounting & invoicing solution.
https://wpinvoicing.com/ - https://wordpress.org/plugins/invoicing/ | Invoicing is a lightweight Invoicing and Payments system for WordPress. It can be used by freelancers to manage their Invoices or by 3rd party Themes and Plugins as their payment system. GeoDirectory currently uses Invoicing as its payment system
Easy and lean invoicing for small businesses, consultants and freelancers, created using AppGini
PHP SDK for integrating with PayPal's Invoicing API
Agora Open source SaaS billing system for software companies
An Open Sourced Invoice System developed for anyone who needs to generate out an invoice and manage clients
This is the development repo for the Sliced Invoices WordPress plugin. (official release repo is at wordpress.org)
WP-Invoice lets you create and send web-invoices and setup recurring billing for your clients.