Ask HN: Freelancers, how do you track your time?

Dear HN,

I've been on quite a journey finding a proper time tracking solution. I'm looking for a simple 'tool' (can be web based, but preferably with OSX client) which allows me to track time for several clients. Some kind of timesheet export would be good. But I don't need a whole business management software with it.

https://www.toggl.com doesn't look too bad, but recurring $5 for a start/stop button? I'm not sure. Maybe if the interface would be awesome.

http://www.flamebrain.com/download-watchme/ is a great little (!) windows app which I have been using a few years back. something like that with timesheets, and for OSX would be it.

http://www.getklok.com/ is horrible UI wise. the features are quite interesting though, but I don't wanna use it.

Aren't there some nice, contemporary open source projects out there? I couldn't find any...

What are you using?