Wave Accounting Software is free for businesses with 9 or fewer employees. Data entered in the program is private and not shared, but advertising from other vendors is visible while the program is in use. Features such as payroll and credit card payment processing are not included in the free application. Email support is available for free Wave accounts, but paid premium support is available.
More information is at https://www.waveapps.com/accounting/.
List of free Wave Accounting features: https://www.waveapps.com/accounting/features/