It looks like we've already followed up with you via email, but here is the information provided for visibility on the forum:
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.
When it comes to calling an API without going through OAuth that isn't possible at this time as there needs to be at least an initial manual authentication to generate API Keys and Secrets which can't be bypassed.
Courtney E. API Support Specialist
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