You can easily export all contacts from ActiveCampaign by taking the following steps:
Step 1: Click "Contacts" in the left menu to go to the Contacts overview page.
Step 2: Click the "Export" button.
Step 3: The "Export Options" modal will appear. You can type the name of the export into the field provided and click the fields you wish to include with the export. Clicking the "Other Fields" checkbox will either select or unselect all fields under it.
Step 4: Click "Export."
The export will start to run in the background and a confirmation message will appear at the top of the page.
Import to Nimble
Click your avatar in the top right hand corner
Choose Networks & Imports
From here, use the Import Wizard to upload your file.
For more information about this feature, please take a look at the following: