What are your experiences with paid ad fill in Safari on iOS vs OSX?


We’ve had some reports for our editors that they see many paid ads in Safari on iOS, but almost no paid ads on a desktop Safari on OSX.

I’ve gathered some data from those who have Macs here, but no data for iOS devices yet, and the trend is that for most people if Safari is their primary browser and they are pre-Safari-11 they get good fill. Post-Safari-11 seems to generally get poor fill. But there are some anomolies that get great fill on Safari 11, even if they use Chrome almost exclusively.

My questions to you:

  1. Have you seen good fill or poor fill for paid ads on desktop OSX/Safari when it’s not the ‘primary’ browser (meaning not used much and therefor doesn’t have a lot of user data cookies)
  2. Do you have any thoughts on why Safari 11 on iOS would have good paid ad fill for a user, but for that same user on Safari 11 on desktop they would get really poor paid ad fill?

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Hey There,

One resource that I found interesting related to the subject was this article:

I know that on mobile, cookies are not the main source for matching readers identities. Mobile ID’s are used more frequently and can be more valuable due to it being static through the life of the phone, as most people do not ever change them.

That could be one reason why the mobile safari would perform better in some cases. I am curious to hear other peoples opinions though.

Hope that helps,


Thanks, Jordan!

I had seen that article, and had suspected that the device AdvertiserID was being exposed when when those third-party cookies were being blocked in Safari 11, but I haven’t found any direct citation online that AdvertiserID is always available in mobile Safari 11.

Do you know of any article that might state that Apple policy is to allow AdvertiserID even when it limits/blocks third-party cookies? My CEO doesn’t trust the ‘suspicions’ of this developer :wink:



This is the most complete reaction to the change that I have found. I am still reading through all the information, but I would be interested to see what you think about it.

It has short term mitigation steps and long term bigger picture ideas. It also has a 'how it affects…" section that breaks it down from publisher, buyer, and SSP standpoint.

Let me know what you think or if you find it helpful. I may do a write up for the community on this subject if this gets some traction or more people let me know they are interested.