We'll create fresh WordPress site with Connect Contact Form 7 to Constant Contact installed. You have 20 minutes to test the plugin after that site we'll be deleted.
Update March 2022. Users may need to update their API Secret and Application by visiting Constant Contact, and updating the settings page on this plugin. See https://v3.developer.constantcontact.com/api_guide/auth_update_apps.html for the release of the Constant Contact Authentication Update.
This is an advanced Constant Contact to Contact Form 7 Connector. This plug-in will allow you to make a connection to Constant Contact’s API using OAUTH protocol. Retrieve all of your contact lists, and allow users to sign up for a single list, or multiple lists. This will update existing contacts in your Constant Contact list, or add new if they don’t exist. In addition to adding or updating E-Mail addresses of contacts in your list, this will also allow you to push basic contact fields, including:
Some uses for this plugin would be to add an optional checkbox to a regular contact form where users can subscribe to a single or multiple CTCT lists. You could also include this with a product registration form, or pretty much make every form on your website a possibility for users to subscribe to your Constant Contact Lists.
Complete instructions can be found How to create an API Key and Token and here How to set up this plugin.