Open-source Service Sales Management App
"Sales is a service sales manager especially for freelancers – built in German, available in English too.
It includes a dashboard showing current trends and tax data, client management, creating projects for clients and provide estimations, creating invoices and fill them with descriptive positions, export quotes or invoices from projects as PDF, keeping track of expenses and taxes, gifts and donations (e.g. if you're an OS maintainer), anonymizing data in staging/dev environments.