How to transfer customer data(name, company name, phone and email) between two companies in quickbooks online?

You can use a migration tool

https://get.transactionpro.com/qbo

Hi sam-greenwoodsup,

Welcome to Community!  QuickBooks Online provides the tools you need to import your data effortlessly.  I'd be glad to assist!

Here's how to export your customers;

1. Open your Settings ⚙ and select Export Data

2. On the Lists tab and move the toggle to on, beside Customers

3. Select Export to Excel.

Here's a detailed guide for your reference, for exporting data, reports, lists and more in QuickBooks Online.

You're ready to import your customers.  Here's how;

1. Select Settings ⚙, then Import Data

2. Click on Customers

3. Download a sample file to ensure your spreadsheet is mapped to the fields in QuickBooks 

4. To upload your saved file from your computer, select Browse and choose the file and then select Open

5. Hit Next

6. Make any necessary adjustments

7. Hit Import

To learn more about importing data click here.

If you have any other questions, please feel free to reach back out.  We're always happy to help!