What is a walled garden?
A walled garden is a closed advertising ecosystem where one company owns the audience, the inventory, the user data and the tools to buy and measure ads. Advertisers can target users with the platform's own logged-in data, but that data rarely leaves the platform. Common examples are Google and YouTube, Meta, Amazon, TikTok and large streaming services.
The name reflects the trade: rich data and scale inside, limited visibility and portability outside.
How walled gardens work
Walled gardens are built on signed-in users. Because people log in to search, shop, watch or scroll, the platform can tie behavior to a known account across devices. That data powers:
Targeting: audiences based on search, shopping, viewing or social activity that outside buyers cannot access.
Buying: ads are usually bought through the platform's own tools, such as Meta Ads Manager, Google's buying platforms or Amazon DSP.
Measurement: reporting comes from the platform itself, often with limited log-level data and limits on independent verification. Formats and placements are also set by the platform, so creative must follow its specs.
Data collaboration: where advertisers can combine their own data with the platform's, it typically happens inside a data clean room that returns aggregated results only.
Some walled gardens also sell access to inventory outside their own properties. Amazon DSP, for example, can buy third-party exchange inventory using Amazon audience signals, and Google's DV360 buys across many exchanges as well as YouTube.
Why walled gardens matter
A large share of digital ad budgets goes to walled gardens because they offer scale, strong first-party data and closed-loop measurement, such as linking ad exposure to purchases on the same platform.
The downsides are real too:
Grading their own homework: the platform sells the ads and reports on their performance.
Limited portability: audiences and insights usually cannot be exported.
Siloed reach and frequency: each garden counts its own users, so overlap across platforms is hard to see.
Dependence: changes to algorithms, policies or pricing can shift results with little notice.
Many advertisers balance walled garden spend with open web buying through a DSP, and use incrementality tests to check each platform's claims.
Walled garden vs open web
The open web is the part of the internet where publishers sell inventory through shared programmatic infrastructure, such as SSPs, exchanges and open auctions, to any DSP. Data and measurement can come from many independent vendors. Walled gardens keep all of that in-house. The open web offers more transparency and flexibility, while walled gardens offer more first-party data and simpler buying. Most media plans now use both: walled gardens for their unique audiences, the open web for reach, control and independent measurement.
Walled gardens with AdGeeks
AdGeeks gives seat-level access to Amazon DSP, which brings Amazon's shopping and streaming signals, and to DV360 and Adform for buying across the open web and premium deals. Our traders plan across both, compare results on consistent measures and shift budget to what performs.
