What is server-to-server (S2S) tracking?

Server-to-server (S2S) tracking is a method of collecting user actions—like clicks, sign-ups, or purchases—by sending data directly between servers. Unlike pixel-based tracking, S2S doesn’t rely on a user’s browser or cookies, making it more reliable and secure.

How does server-to-server (S2S) tracking work?

When a user takes an action on a website or app, that event is recorded and passed directly from one server to another. It all happens behind the scenes—no cookies or browser dependencies. 

Types of server-to-server (S2S) tracking:

• Postback: A type of S2S integration that sends data from one system to another. It only works as one-way communication; it sends data but doesn’t wait for a response or acknowledgment.
• API: A more flexible and dynamic connection between systems. In particular, an “Event API” sends, receives, and processes event-based data in real-time. It allows systems to track specific user actions (events) as they happen and share that data instantly with other platforms.

APIs vs. Postbacks

Think of an API like a conversation. You ask for something (request), and you get an answer (response). With APIs, there’s two-way communication, meaning the system can send and receive data, and can also retry if something goes wrong.

In comparison, a postback is like a receipt—it just confirms something has happened but doesn’t request or send any further information. It’s a one-way notification and does not provide an option to retry if an error occurs.

How to measure server-to-server (S2S) tracking:

With S2S tracking, measurement is based on server logs and real-time data exchanges. It provides a clearer and more accurate picture of user behavior. Key metrics include:

• Conversion rates: The percentage of users who complete a desired action, such as making a purchase or signing up. With S2S, conversions are captured directly from server events, reducing the risk of missed or duplicated data.
• Event completions: Tracks specific actions like app installs, purchases, or form submissions. Because the data is passed directly between servers, you can capture even complex multi-step events without relying on browser behavior.
• Attribution accuracy: Determines which channel, campaign, or partner drove a user to convert. S2S provides more precise attribution since it avoids common pitfalls like cookie loss, ad blockers, and browser restrictions—resulting in cleaner, more reliable insights.

Why is server-to-server (S2S) tracking important to marketers?

S2S tracking delivers higher accuracy and reliability, especially in a privacy-focused world. It enables cross-device tracking, reduces data loss, and gives marketers a clearer view of customer journeys. This helps optimize campaigns, improve attribution, and ultimately drive better ROI.

Who needs to know about server-to-server (S2S) tracking?

Anyone involved in digital marketing strategy or measurement should understand the benefits and mechanics of S2S tracking, including:

• Growth Marketing Lead
• Data Analyst
• Marketing Operations Manager
• Software Developer
• Product Manager

Use server-to-server (S2S) tracking in a sentence:

“We upgraded to server-to-server tracking to improve attribution accuracy and avoid losing conversion data for our post-transaction advertising campaign.”