I built my own time tracking tool (<a href="https://logmyhours.com" rel="nofollow">https://logmyhours.com</a>) for tracking my time and creating invoices for any side freelancing I was doing. I'm actually hoping to go full time on this in the next 6-12 months.<p>I use a bit of Trello and Freedcamp for my todos and planning.<p>I also use RescueTime to make sure I'm keeping productive. I'm actually exploring adding integrations with RescueTime with LogMyHours, to see how productive you were for each timesheet, and reporting period.
I have a LibreOffice spreadsheet which I fill out my hours in. I also have a Writer document with my invoice layout and an embedded spreadsheet which lets me add line items and automatically calculates taxes. Easy enough to export to PDF. I keep all invoices in a specific directory, their filenames starting with the date and client name for easy discovery. I add the word '-PAID' to the filename once the invoice is paid by the client.
<a href="https://www.getharvest.com" rel="nofollow">https://www.getharvest.com</a> works well for me. Web plus a native osx app and ability to log and remove idle time in case you leave it's timer running.
I use Trello for task management and Harvest for time tracking and billing. I sometimes get envious of people with more tightly integrated and automated systems but so far I have needed the flexibility that comes with looser coupling much more than I've missed the added time required by my current setup.
I use <a href="https://wakatime.com" rel="nofollow">https://wakatime.com</a> to automatically show how long I worked on each project. The invoicing tool is in private beta right now, but it's basically an easy way to create a PDF for sending to clients.
I built Bx - it's a fair bit more than just time tracking, but it covers time tracking nicely. Try it out at <a href="https://usebx.com" rel="nofollow">https://usebx.com</a>