TikTok has the most complete public ad library: Mozilla report says

By John Koetsier April 16, 2024

According to a massive new Mozilla report on tech platforms’ ad libraries, TikTok has the most complete public ad library. However, Google, Apple, and Meta are right behind the short-video platform in terms of providing the most complete and functional tools to provide transparency into ads placed on their platforms. 

The bad news according to the report: none of the big tech companies ad libraries are completely functional yet, and some platforms — like X, the former Twitter — have huge gaps.

The EU’s Digital Service Act requires large online platforms to publish constantly updated ad libraries. The goal is to ensure no one is unduly impacting elections or other matters of public policy. Any platform that reaches more than 10% of the 450 million people in Europe qualifies, so that means a large number of American and international companies have to comply with this guideline.

The list includes:

  • AliExpress
  • Google
  • Apple App Store
  • Bing
  • LinkedIn
  • Meta
  • Pinterest
  • Snap
  • TikTok
  • X
  • Zalando

Ranking each ad library: the criteria and the results

Mozilla ranked each online platforms’ ad library by 13 criteria, including public accessibility, content of ads, duration of availability, searchability, ad performance data, documentation on how to access the information, and insight into who saw the ads.

At a high level, here’s what they found:

ad library rankings

(A blank cell means the functionality does not exist; red indicates a significant lack or problem; orange indicates minimum functionality; yellow indicates there is still a big gap; green means everything is provided.)

Since it’s hard to total up a visual like the one above, I assigned a score to each color:

  • Blank = 0
  • Red = 1
  • Orange = 2
  • Yellow = 3 (I may be color-blind, but I don’t see any yellow in the chart above)
  • Green = 4

Considering them less relevant for a user acquisition audience, I threw out Zalando, LinkedIn,, and AliExpress, then manually totaled up the rows (unfortunately GPT-4 was completely unhelpful with this manual drudgery).

The result: the TikTok ad library wins, followed closely by Google, Apple, and Meta.

Large platforms' ad libraries ranked

Bing, Pinterest, and Snapchat all have some work to do, while X simply provides a CSV file and no web interface to check online ads.

Ad library usefulness: not just political

Of course, there’s a lot more an ad library could be used for other than checking for political ads or well-funded public policy pushes. It’s also an inexpensive way to keep tabs on competitors: see what ads they’re running, where, and how many.

Right now, honestly, an ad intelligence tool is your best bet for this. It’s just going to be easier and quicker to get the information you want. But if your budget is $0 and your needs are minimal, an ad library is very useful.

They could get more useful, too.

The EU has guidelines on what an ad library for a large online platform should look like, and the Mozilla report says there’s some room for improvement. Currently, here’s the requirement:

  • Content of the ad
  • Advertiser details
  • Duration of the ad campaign
  • Targeting parameters
  • Influencer’s paid posts
  • Number of people who saw the ads

Check First, the organization Mozilla hired to check the data and build the report, says that ad libraries should offer more comprehensive data and easier ways of accessing and slicing it up. That includes:

  • Filtering
  • More targeting information including segmentation
  • Historical data
  • Campaign details
  • More advertiser information
  • Creative content descriptions

This proposal may or may not be adopted by the EU, and it would involve significant effort from the platforms to enable, but it would make everything much more usable.

Room to improve

It’s a safe bet that given the current regulatory environment, the EU will require platforms to provide more data and probably easier access to slicing and dicing it. 

Mozilla says Apple could provide more detail on country breakdowns, Google could provide access by keyword, Snap should provide an API and better search, and TikTok has room to improve on accuracy.

That said, we’ve come a long way in the last 5 years:

“Now, 11 of the world’s largest tech companies have ad repositories. The road here has not been smooth, but this is progress,” the report says.

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