Glossary
What is an ad library?
Definition
An ad library is a public, searchable archive of the advertisements running on a platform, such as the Meta Ad Library or the Google Ads Transparency Center.
Ad libraries exist because of political pressure, not marketer demand. After the scrutiny that followed the 2016 US election, Meta launched a searchable archive of political ads in 2018 and extended it to all ads in 2019. Google followed with its Ads Transparency Center in 2023, and the EU’s Digital Services Act now obliges large platforms to maintain public ad repositories. TikTok and LinkedIn run their own.
What you get: the creative itself, the copy, run dates, placements, and the advertiser’s verified identity. What you mostly do not get: spend, reach, and targeting detail, which are disclosed only for political and issue ads in most regions, and performance data of any kind. The sharpest limitation is memory: a standard commercial ad disappears from the archive once it stops running, so the public record is a window, not a history.
For practitioners, the libraries are the primary source for competitor creative research, and because the native archives stop at search boxes, a market of ad library tools has grown on top of them. The market splits in two: swipe-file tools for creative teams who browse, save, and tag reference ads, and intelligence tools for structured, cross-platform data with stored history and API output, since Meta’s official API is scoped mainly to political ads and Google’s has none. Checking libraries by hand does not scale past a couple of brands, and because the history evaporates, whatever you did not capture is gone.
How this shows up in Waldo
Waldo scans the Meta and Google ad libraries daily for every tracked brand and stores what it finds permanently: creative, copy, and run dates survive after the ads leave the public archive, and every stored ad keeps the native library’s own id and deep link back to the source. One scan alone returned 14,793 Meta ads, and the same API reaches the LinkedIn and TikTok libraries on demand. The discover_ads MCP tool and its per-platform siblings run the same searches from inside Claude.
Related terms and reading
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