Firefly III

Firefly III is a free, self-hosted personal finance application built on PHP and JavaScript that implements double-entry bookkeeping, the accounting standard used by businesses. It tracks both sides of every transaction so you can reconcile accounts with precision and maintain audit-ready financial records. Since you host it yourself on your own server or a rented instance, your financial data never travels through third-party servers.

Freelancers working with irregular income or managing multiple income streams find Firefly III invaluable for tax preparation and expense analysis. It's more complex than simple budget trackers, but that complexity pays off if you need detailed transaction histories and the kind of data control that comes from owning your own infrastructure.