I love Freshbooks, and have just (this past week) upgraded to the paid version because of client load (does the

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I love Freshbooks because:
I could not find an integrated time tracker with a start/stop that I liked as much as Freshbooks, which was a huge draw for me.
Clients can log in whenever and see tracked time on projects that you have set visible.
Also, FreshBooks integrates with BaseCamp, which I use for project and client management, so it works very well for my needs.