What does your software do?
It creates a timesheet based on your git history, and then creates an invoice from that. It guesses the number of hours you've worked an any given day, and also shows you your work for that day and allows you to correct the estimate.
It used to take me an hour to create an invoice - now it takes about a minute.
It's not a huge savings - but for those like me who dread creating invoices it makes me happy to get it done quicker.
Of course the tool is worthless unless you are a programmer checking all of your work into git. I'm trying to find out if this thing could be useful to people other than me.
I don't freelance, but I do bill hourly for consultancy work. I just calculate the number of hours in my calendar I've assigned, and work from that. It takes minutes per month (and I know what I'm doing based on the calendar).
In some cases lawyers bill by the minute. I'm not sure they use a specialized tool, and imagine it's more like an Excel sheet with time of call.
Sounds like an interesting technology, but limited not just to freelancers who use Git, but freelancers who use Git and have a similar workflow you use (and those that have a different workflow could raise hell regarding it not working for them, especially as it's about how much they request to get paid).
I also doubt many billed clients would like to hear their billable time was guessed or estimated.