For any small business or freelancer, keeping track of the client invoices and payments is a job that is handled personally.
Using an online invoicing solution can help minimizing the effort spent on the task and, FusionInvoice, a free + open source invoicing app can help.
FusionInvoice is built with PHP/MySQL and has a simple-yet-nice interface.
Using the app, we can define clients, send quotes, convert quotes to invoices or create and send the invoices directly. Invoices can be set as “recurring” as well.
As a payment system, there is only support for PayPal and any other payment provider will require some custom coding.
In the dashboard, it is possible to filter records, view reports and also create guest users (like clients) which only has read permissions so that they can view their invoices and payments too.