PayPanther is a popular web base contact management, CRM and invoicing solution targeting freelancers. In comes with a number handy features ranging from time tracking to expense logging. Basic project and document management is available as well. Bitrix24 is a free PayPanther alternative that lets you choose between cloud and on-premise (self-hosted) deployment, provides access to the source code and comes with a number of collaboration tools that aren't available in PayPanther. Please see this chart to decide if Bitrix24 is what you've been looking for.
Using Bitrix24 as PayPanther alternative
* Please note that the information may have changed since the publication. For current prices and features please visit Bitrix24 pricing page.