For invoicing at my small business, I use Invoice Ninja.
Open source, self-hostable, and they offer cloud hosting. Free for the base version with less than 20 users. It has a bunch of features, you are able to create very professional invoices, define services and products, calculate taxes, fees, etc.
It’s very clean, fast, and intuitive.
For accounting, I use GnuCash. It’s old looking and clunky, but it has a bunch of features and works fine for everything I need.