While getting set up with the app marketplace, I added a check for referral_code during the oauth process - read somewhere while setting it up that the field would be filled when a user is referred by the marketplace. Just got my first customer from there, and had to manually track it because nothing came in through that field. What’s the standard way to know a customer came from the app marketplace? I can’t imagine I dreamed up an API call that would send me a referral_code field, did I? 
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I’m not sure I fully understand the question. We don’t have any referral_code tracking APIs. Any referral agreement is tracked internally. If you could further explain what exactly your looking for I’ll be able to assist.
I’m starting to think maybe I dreamt it When I was working to get my site ready to be in the App Marketplace, I read somewhere that Square would send referral_code in addition to normal info when the user had clicked to come to my site from the App Marketplace listing. Specifically referral_code, it wasn’t referencing utm_source or anything.
Does the App Marketplace add anything to any API calls? (I literally coded my site to pick it up during the oauth connection process, so it must have had something to do with that)
Or, do I need to listen for the ?utm_source querystring val and keep ahold of that until they create an account, then tag them appropriately?
I’m not aware of anything that you can listen to. I know the team should have provided a unique link for tracking our our end but I’m not aware of anything that you can configure to listen to on the client side.
Sorry, not to track my referrals to Square. I need to track referrals from the App Marketplace to me, which is why I was excited to learn that the referral_code option was in the oauth handshake, so I could just listen there and not have to track stuff on the front end. Sounds like I’m just crazy, and should track those links the old fashioned way, lol