I'm working on a web app that uses a javascript tracking pixel to collect information from users that visit a website (user ID, browser, etc.).
I want to be able to retarget the same users through Facebook ads but without placing the Facebook pixel on the site. Is there a way of doing that with the Facebook Marketing API? If not, then how do companies like Criteo and Adroll do it with their own pixel?
If you can collect public PII like email, name, AAID/IDFA, etc., you can upload them to Facebook and create a custom audience from that. But user IDs specific to your own website won't work because Facebook won't be able to match those.
If not, you have to have FB Pixel installed to communicate to FB the user's identity via browser cookie.