For the past 2 years I've used Freshbooks. I work full time at a company and only have 3 side customers so I use the free option. It works unbelievably well.

For the past 2 years I've used Freshbooks. I work full time at a company and only have 3 side customers so I use the free option. It works unbelievably well. They're even adding more accounting functions to the great functions hey have today.