There are a variety of third-party applications that works with QuickBooks Online (QBO) to help you run your business. To sync your Joist data (i.e. contacts, clients, estimates, invoices, and income) to your QBO account, I'd recommend contacting the Joist Support team. They have their QuickBooks sync feature where it lets you transfer files into the system. This way, you can effectively manage your transactions.
In the meantime, you can find the right apps for your business by checking out this article: QuickBooks Apps. It groups them according to their categories like make payments, managing customers, prepare taxes, and sync data to name a few.
Additionally, you're also able to manually import your data to QBO. To know more about this, kindly refer to this article: Importing data to QuickBooks Online. It contains answers to the most frequent;y asked questions about the file format and information that you can import to the system to name a few.
Please don't hesitate to comment below if you have other concerns or further inquiries about managing your transactions using third-party apps in QBO. I'm just around to help. Take care always.