Can I get contact list from an existing account

[JasonS2369]

I have a customer who already has a Constant Contact account. They want to be able to programmatically add signups from their website to an existing list in Constant Contact. I'm assuming I will need to have them authorize the app to grant access to the application? Am I on the right page? Once I do that, I can query for the list and then add/sync users to the list?

[Courtney_E]

Hello JasonS2369 ,

Thank you for reaching out to Constant Contact API Developer Support. My team is here to assist outside software developers with questions about building into Constant Contact's API.

There are a few different ways that you can accomplish connecting a website sign-up form to Constant Contact. I’ll list them for you below:

Option 1:
If their website is currently using an existing 3rd party sign-up form that you want to connect, you’d want to refer to the documentation for that form to see if it is able to connect to Constant Contact and which version of our API it uses to make that connection. We have two different versions of our API, so the steps you take to get this information will depend on what version of our API the integration you are looking to connect with uses. I’ll also include the steps to get the list identifiers for each version if that is not something that the form that you are using pre-populates for you.

• If the app you are using is asking you for an API Key and Secret, you can find the steps to generate a V3 API key by clicking to expand the section “How do I Get an API Key?” at this link:
  https://developer.constantcontact.com/api_guide/faqs_manage_applications.html
• How to get list IDs for the V3 version of the API:
  https://v3.developer.constantcontact.com/api_reference/index.html#!/Contact_Lists/getLists

• If the app you are using is asking you to also provide an API key and Access Token, please follow the steps at the following link to create a V2 API key instead:
  https://community.constantcontact.com/t5/Community-News/How-to-generate-an-API-Key-and-Access-Token/...
• How to get list IDs for the V2 version of the API:
  https://v2.developer.constantcontact.com/docs/contact-list-api/contactlist-collection.html?method=GE...

Option 2:
If you are looking to develop your own custom sign-up form integration from scratch, we offer all developers free access to our API endpoints to allow them to build their own forms and integrations between Constant Contact and other software/platforms.

Getting Started with V3 API
https://v3.developer.constantcontact.com/api_guide/index.html

Option 3:
We also offer a variety of pre-built sign-up forms through Constant Contact that you can design through our site, and then just paste the HTML code into your website:

• Inline form:
  https://knowledgebase.constantcontact.com/articles/KnowledgeBase/18265-Create-a-Sign-Up-Form-with-th...
• Pop-up form:
  https://knowledgebase.constantcontact.com/articles/KnowledgeBase/21407-Create-a-Pop-up-Sign-Up-Form
• Landing Page form:
  https://knowledgebase.constantcontact.com/articles/KnowledgeBase/32012-Create-a-Lead-Generation-Land...

Please have a look and let us know if you have any other questions!