Harpoon Revenue Goal Calculator - Freelancers, how much money do you need to make?
Stripe Atlas Taxes - Help file your business taxes
Hourly Rate Calculator - Find out your ideal hourly rate
Taxfyle - Stop doing your taxes, leave it to the professionals.
Quarterly Tax Calculator Bot - Quarterly tax calculation for freelancers
neo.tax - automated R&D tax credits for startups = extra month of burn