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 is currently no way to bypass the initial Authorization Request screen and redirect, which can only be accessed/authorized via a browser window, but you should only need to authorize an account once.
However, it looks like your account may be part of a Partner Group with Constant Contact:
Specifically for Partner accounts, we now offer the new option of acquiring a “Master Token”, which allows you to send API requests on behalf of Partner managed client accounts without needing individual access tokens for each child account.
However, in order to utilize the master token, you will likely need to make significant changes to your application’s existing code, as instead of using the the standard Oauth flows and storing tokens for each child account, you would be using the Partner authorization method to get a Partner API access token (JWT), then using that to call the "pass-through" Partner endpoint.
If you decide to go this route, please let us know the API key that you will be using for your application (by emailing us securely at email@example.com along with the URL link to this post for reference) so that we can grant it the correct permissions.
Technology Partner Registration
Technology Partner Authentication and Authorization
API Reference - POST Send an API request on Behalf of a Client Account
Alternately, if you at all anticipate potentially needing to be able to connect your integration with with an account that is not directly under your partnership, and/or don’t want to have to fully re-code your application, the other option would be to utilize the Redirect URI within your application’s flow so that each client can connect their own account and grant permission, rather than you having to get each account’s login credentials. Essentially, each connected account would need to grant access and your application would need to store each of these token sets for making calls to each connected account.
When a user goes to connect their Constant Contact account to your integration and clicks “Allow” on the Authorization Request screen to grant your app access to their data, they are sent to the website URL that you specify as your Redirect URI. After the account owner is successfully authenticated and authorizes your application, Constant Contact redirects the account owner to your chosen redirect_uri and appends the Authorization Code to the URL, allowing your application to capture it and exchange it for your initial token set.
Get the Token from the Redirect URL
Create an Authorization Request URL
Please have a look and let us know if you have any other questions!
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