Hello FirstNameL05517,
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. After you complete the OAuth2 server flow for V3, Constant Contact returns an access token and refresh token. You can use access tokens to make requests using the V3 API, and you can use the refresh tokens to obtain new access tokens without any user input. This ensures that you only need to authenticate the account you’ll be connecting to once. After the initial authentication, you’ll just use the refresh token and access token to complete your future requests. V3 API OAuth2.0 Server Flow https://v3.developer.constantcontact.com/api_guide/server_flow.html Tokens Overview https://developer.constantcontact.com/api_guide/auth_overview.html#tokens
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