Not open source but free with many features, https://www.waveapps.com/ https://www.waveapps.com/ can fit the bill for many small businesses. However, it may no

Not open source but free with many features, https://www.waveapps.com/ https://www.waveapps.com/ can fit the bill for many small businesses. However, it may not scale the way QB does, and folks you bring on won't have had experience with it's way of doing things. That being said, with QB's changes, chances are that's true of QB folks as well (ha, ha).