InvoicePlane is an open-source invoicing application designed to manage quotes, invoices, payments, and clients efficiently. It is ideal for freelancers and small to medium-sized businesses seeking a customizable and self-hosted solution for their invoicing needs. The software offers features such as invoice templates, client management, and payment tracking, and it supports multiple languages and currencies. InvoicePlane can be easily installed on any web server with a PHP and MySQL environment.