Mobile & app · also called Software development kit, ad SDK
SDK (software development kit)
An SDK (software development kit) is a package of pre-built code developers add to apps to provide features, such as showing ads, measuring installs or analytics, without building them.
In mobile advertising, SDKs are how third parties get inside apps. An ad network's SDK requests and displays ads; a ad mediation SDK manages many networks; an MMP SDK reports installs and in-app events for attribution; the Open Measurement SDK enables verification; analytics SDKs track usage.
SDKs are convenient but come with costs. Each adds app size, potential crashes and battery use. More importantly, they run with the app's permissions, so they can collect data. Some SDKs have been caught harvesting location, contacts or usage data, and some have been found committing fraud, such as click injection or loading hidden ads. Apple now requires privacy manifests and signatures for commonly used third-party SDKs, and Google Play requires developers to declare data collected by SDKs in their apps.
On the other side, fraudsters may impersonate SDKs by sending fake messages to measurement servers, known as SDK spoofing. App developers should choose SDKs carefully, keep them updated and understand what data each one collects.
Think of it like this
An SDK is like a ready-made kitchen appliance you install into your restaurant: it saves time, but you are letting another company's machine into your kitchen.
An example
A fitness app includes six SDKs: two ad networks, a mediation platform, an MMP, OM SDK and crash analytics. An audit reveals one ad SDK collecting precise location, so the developer removes it.
Related terms
MMP (mobile measurement partner)
An MMP (mobile measurement partner) is an independent company that attributes app installs and in-app events to the ads and ad networks that drove them, and detects mobile install fraud.
Ad mediation
Ad mediation is software that lets app developers connect many ad networks and bidders through one SDK and chooses which network fills each ad request to maximise revenue.
SDK spoofing
SDK spoofing is mobile ad fraud in which fabricated install or in-app event messages, mimicking a real measurement SDK, are sent straight to attribution servers without any real device or user.
Open Measurement SDK (OM SDK)
The Open Measurement SDK (OM SDK) is an IAB Tech Lab standard toolkit that lets verification vendors measure viewability and invalid traffic inside apps and other environments through one shared integration.
In-app advertising
In-app advertising is ads shown inside mobile apps, such as games, utilities and social apps, as opposed to ads on websites viewed in a mobile browser.
Sources: IAB Tech Lab Open Measurement SDK, Apple: User privacy and data use