SDK in AdTech: what it is, how it works, and when a custom SDK makes sense

The average app developer works with 14 to 18 SDKs (Software Development Kits) in a typical mobile app stack. That's the reality of building apps today. 

In addition to SDKs used for analytics, attribution, payments, and other functions, mobile apps also rely on AdTech SDKs. To monetize inventory, a mobile app owner typically integrates an SDK provided by an ad network or monetization platform. Many publishers also integrate a mediation SDK to manage multiple demand sources more efficiently. Supporting multiple SDKs or adapters increases app size and can add maintenance overhead while impacting performance and user experience if not properly optimized.

Building a custom SDK or adopting a white-label one is relevant primarily for companies that operate their own monetization infrastructure. This will be covered later in the article.

Quick answer: what is an SDK in AdTech?

An SDK in AdTech is a set of pre-built tools integrated into an application to handle advertising functions. This includes sending ad requests, collecting and transmitting advertising identifiers where permitted. It also includes collecting event data and reporting impressions and clicks. These SDKs make app inventory available to demand partners through real-time bidding or hybrid mediation environments that combine in-app bidding and waterfall demand. Every monetization solution has its pros and cons: in a related article, we've compared AdMob vs AppLovin MAX vs ironSource for you.

A white-label SDK offers greater control and ownership than an off-the-shelf one. It can be used to connect mobile inventory to a white-label SSP infrastructure for mobile publishers through a standardized integration layer. Alternatively, it can coexist with existing monetization SDKs, allowing publishers to retain third-party demand while introducing their own demand sources. In this context, a custom-built SDK offers significantly greater control — but the company must build, maintain, and evolve it in-house.

What іs an SDK? Core definition and components

An SDK is a packaged set of resources — provided by a hardware or software vendor — that lets developers build for a specific platform, device, or service without starting from raw code.

SDK components — reference guide

This is also where SDK vs API confusion usually comes from: an API is a door between two systems, while an SDK is the whole house — everything a developer needs to build something that uses that door. An API is just one component of an SDK, not the other way around.

In software development kit advertising, this same structure applies — except that the service being integrated is a monetization ecosystem. Whether that SDK is pre-built by a monetization partner or part of a custom SDK mobile advertising setup depends on how much control a company needs over that ecosystem. With a custom-built SDK, that control comes with full ownership. 

AdTech SDK: three types you need to know

Off-the-shelf SDKs — the kind supplied by ad networks or mediation providers — help a publisher get up and running quickly. But they come with real limits, including a fixed set of supported ad formats, varying levels of access to bid-level and auction data, and a dependency on the vendor's update cycle.

Custom and white-label SDKs solve this differently, but only for companies that already run their own monetization infrastructure.

• A custom-built SDK gives a company significantly greater control over its own ad formats, data handling, auction logic, and monetization rules. The trade-off is that the company has to build and maintain it in-house. 

• A white-label SDK offers many of the same benefits without requiring in-house development. It provides the integration layer between app inventory and the underlying white-label SSP.

From what we've seen working with publishers, the push toward custom or white-label setups is rarely about scale alone. One common reason, among others, is the need for direct access to bid-level data. Companies also want to set their own monetization logic rather than work within someone else's fixed ruleset.

Custom SDK vs white-label SDK vs off-the-shelf SDK

For most companies evaluating mobile SDK ad integration, the decision comes down to one question: do you want to rely on someone else's monetization stack, or run your own? For companies that decide to go their own way in programmatic and launch their own monetization infrastructure rather than rely on an off-the-shelf in-app SDK advertising, adopting a white-label SDK is often a viable option.

SDK in AdTech: key industry stats

SDK adoption in mobile AdTech isn't evenly distributed — a handful of providers dominate. The gap between "most installed" and "most monetized through" tells its own story about software development kit advertising today.

• In-app advertising is the source of income for 24% of U.S. apps and 27% of global apps.

• Google AdMob is the leader, integrated into over 88% of Android apps that use a standalone ad network SDK (excluding mediation adapters), with Facebook Audience Network a distant second at roughly 24%.

• AppLovin MAX, Unity LevelPlay, and Google AdMob together control more than 90% of the mediation market, leaving a long tail of smaller providers to split the rest.

What this means in practice: most publishers work with the same handful of providers. Adding a second ad network SDK or a mediation adapter is usually about diversifying demand sources. This might capture the impression opportunities that the first network doesn't monetize, improving fill rates and increasing revenue. The trade-off is added complexity — more SDKs to maintain, test, and keep up to date. Building a custom solution or adopting a white-label solution is a different decision entirely — it means the company already has its own monetization infrastructure to run.

Use cases of SDKs in AdTech

Here are the three areas that cover most of the SDK use cases AdTech developers encounter in practice.

1. In-app mobile advertising. This is the largest segment by far. Rewarded video, interstitial, banner, and native ad formats are all delivered through SDKs embedded directly in the app. The SDK handles ad requests, receives creatives, and renders them using the appropriate display or playback components — whether that's a full-screen interstitial between game levels or a banner at the bottom of the screen.

2. Programmatic video advertising. SDKs support video monetization in mobile apps by managing ad requests, playback tracking, and VAST compliance. Accurate measurement is especially important for video inventory, where ad delivery must stay synchronized with content playback.

3. In-app header bidding. Since mobile apps lack a browser header for inserting code, SDKs provide the integration layer that enables in-app bidding frameworks. The SDK-based bidding frameworks allow multiple demand sources to compete simultaneously for the same impression — a real-time auction, rather than the older waterfall model that called networks one by one. For app developers managing multiple ad networks and demand partners, this is usually where a programmatic advertising strategy starts to take real shape.

Across all three cases, the broader pattern holds: SDK monetization depends on how well the SDK is integrated, not just which one is chosen. That's especially true for app developers running multiple ad formats or demand sources at once. The same principle applies to companies that decide to operate their own monetization infrastructure, where custom SDK mobile advertising or white-label SDKs provide greater control. 

Conclusion

AdTech SDKs sit at the center of how mobile inventory actually gets monetized. Most mobile monetization setups rely on SDKs to connect the app to a monetization provider — typically an ad network or mediation platform. In some cases, mediation SDKs rely on lightweight adapters to coordinate integrations with individual networks.

For most apps, an off-the-shelf SDK from a mediation provider is the right starting point — it gets monetization up and running quickly, without engineering overhead. For businesses that operate their own SSP infrastructure, a custom or white-label SDK is often the preferred way for publishers and app partners to connect to it.

If you’re interested in launching a programmatic business and monetizing mobile apps, we recommend going with a white-label SSP paired with a white-label SDK. Our team will partner with you to grow this business: we’ll handle all the technical aspects, leaving the business side entirely up to you. We can also develop a custom AdTech platform — for example, a monetization solution with DSP functionality, so advertisers can bid directly on your inventory. 

Interested in learning more about what we can do for you?

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