Yes, Ecwid allows to import products using CSV files. Therefore, you will need to export your products from opencart in CSV file first. You should remember that CSV file should be created in suitable for Ecwid format. Please, refer to this article for details: http://kb.ecwid.com/w/page/26373353/Import-Export
Unfortunately, Ecwid don’t have functionality which allows to import customers list yet. But you can easily add your customers manually in the store front. This will looks like your customer came to your store and registered by himselves. For store registration you will need to enter customers Name, Email and Password (any sequence of symbols). Before you will start to add customers, you will need to change notification message a bit, because Ecwid don’t send passwords in customer’s notification by default.
In order to add this information you should:
1. Go to Ecwid control panel → System Settings → Mail → Customer notifications
2. Click “Edit message” opposite “Successful registration” line
3. In pop-up window you will see the template of this notification, which can be changed as needed
4. In our case you will need to add following code after Your email: %email%
Your password: %password%
5. Click “Save” button.
Once you change notification template, you should go in your store front, click ‘Sign in’ → “Create new account”, than enter Name, Email and Password (you can use simple sequence like “12345” and ask your customers to change it after first login or generate strong passwords using one of online programs
) and click “Register”. After that, your customers will get notification about registration in your new store and password, which has been used for registration.
In order to register one more customer click “Sign Out” and repeat above actions again.
If you need a professional help with transferring your store from Opencart to Ecwid, I recommend you to use our “Migrate me to Ecwid” service