Today’s customers don’t stick to one device, and neither should your marketing. A shopper might browse your website on their phone during lunch, open your email on a laptop later, and finally make a purchase from a tablet at night. If your tracking stops at a single device, you’re only seeing part of the picture and missing big opportunities.
Cross-device tracking changes that. It gives marketers and growth teams the ability to follow a single user’s journey across phones, laptops, tablets, and even multiple browsers. Instead of fragmented data and broken funnels, you get a complete, connected view of how customers interact with your brand.
For growth hackers, this is a goldmine. With the right tools, you can personalize campaigns more precisely, retarget more effectively, and measure ROI with greater accuracy.
In this guide, we’ll break down what cross-device tracking is, why it matters, how it works, and how to use Opensend as a powerful growth lever for your business.
Cross-device tracking is the ability to recognize and follow the same user as they move between devices and across different browsers or apps. Instead of treating each session on each device as a new, anonymous visitor, cross-device tracking connects the dots to form a unified view of the customer journey.
In a world where people constantly switch between devices, this kind of tracking is essential. A user might first discover your brand through a social ad on their phone, later revisit your site on a desktop to read reviews, and finally complete their purchase on a tablet after clicking a retargeting email.
Without cross-device tracking, those interactions would look like three different people, leading to inaccurate data, poor personalization, and missed revenue. By linking these interactions to a single identity, marketers gain a much clearer understanding of behavior, intent, and conversion paths.
Cross-device tracking allows you to personalize experiences based on the full customer journey, not just isolated sessions.
Traditional tracking methods — like cookies, session IDs, and device-specific pixels — were designed for a desktop-first internet. They work well when a user stays on the same device, in the same browser, without clearing their history or switching tabs.
But today’s users don’t behave that way. They move fluidly between devices and browsers throughout the day, creating gaps and blind spots in the data.
Here’s where it breaks down:
The result? Broken funnels, misleading attribution, and wasted ad spend. You might see a click from a Facebook ad and a purchase on your site, but not realize they came from the same person. This leads to underreporting of performance and poorly optimized campaigns.
Cross-device tracking connects user activity across multiple devices by identifying the same individual behind different sessions. It typically works using one of two main approaches: deterministic and probabilistic tracking.
This method relies on clear, consistent identifiers, such as login credentials, email addresses, or phone numbers. If a user logs into your website on both their mobile and desktop devices, deterministic tracking can confidently link those sessions to a single identity. It’s highly accurate but depends on users authenticating themselves across platforms.
When logins aren’t available, probabilistic methods analyze behavioral patterns, IP addresses, device types, and other signals to make an educated guess about whether two sessions belong to the same person. While less precise, probabilistic tracking helps fill in the gaps where deterministic data isn’t available.
Platforms like Opensend combine both approaches using a proprietary identity graph — a database of consumer profiles built from millions of data points. This allows marketers to match anonymous sessions to known profiles with high accuracy, even when users don’t log in.
Cross-device tracking also has to navigate privacy and compliance requirements. Consent-based tracking, data encryption, and opt-out controls are now standard, ensuring user trust and regulatory alignment.
For marketers and growth teams, cross-device tracking unlocks a more accurate, complete view of the customer journey. This means smarter decisions, better personalization, and higher ROI.
One of the biggest advantages is improved attribution. Instead of guessing which touchpoint led to a sale, cross-device tracking helps you connect the dots across ads, emails, and on-site actions, even when those actions happen on different devices. This gives you a true picture of what’s driving conversions and allows for better optimization of your marketing spend.
It also enhances personalization and segmentation. When you know that a user who clicked an email on their laptop also viewed a product on mobile, you can create more relevant, timely messages across channels.
With platforms like Opensend, you can retarget the same individual with consistent messaging across email, SMS, ads, and even direct mail — no matter where they last interacted.
Cross-device tracking isn’t just a technical upgrade — it’s a practical growth lever that can dramatically improve how you engage and convert users.
Here are a few real-world use cases where cross-device visibility drives smarter, more profitable marketing:
A user adds items to their cart on mobile but doesn’t check out. Later, they open a reminder email on their laptop. Without cross-device tracking, those actions appear unrelated. With it, you can seamlessly trigger a personalized email that leads them back to their cart, regardless of device.
Someone views a product on a desktop and later scrolls through Instagram on their phone. With a unified profile, you can serve consistent, relevant ads based on their full behavior, not just isolated sessions.
Cross-device tracking helps you understand how different touchpoints work together. Maybe a customer first clicked a Facebook ad on mobile, then read a blog on desktop, and finally purchased via a Google search. This insight allows for better budgeting and campaign planning.
With Opensend, these scenarios become easy to execute. Opensend identifies users across devices and connects their sessions to a single profile, enabling growth teams to automate cross-device re-engagement and unlock greater marketing efficiency.
Retention is just as important as acquisition, and cross-device tracking plays a critical role in keeping customers engaged over time. Today’s users expect seamless, personalized experiences no matter how or where they interact with your brand. If you lose track of them when they switch devices, you risk losing their attention altogether.
Cross-device tracking ensures you maintain context and continuity throughout the customer journey. For example, if a customer frequently shops on their phone but reads your emails on desktop, you can tailor your follow-up messages based on their most recent behavior, no matter the platform.
It also enables timely re-engagement. If a customer hasn’t purchased in a while, you can spot that behavior even if they return anonymously on a different device and trigger retention campaigns across email, SMS, ads, or even direct mail.
Opensend makes this process effortless by linking customer activity across devices and recognizing returning users through its identity graph. It allows you to re-engage customers based on real-time behavior, not just a last-known session, helping prevent churn and keep your brand relevant.
Getting started with cross-device tracking might sound complex, but with the right tools and strategy, it’s easier than you think — and the payoff is huge. The first step is to ensure you’re collecting high-quality first-party data. This includes email addresses, login events, phone numbers, and behavioral data like page visits and cart activity.
Next, integrate your core platforms — such as your CRM, ESP (email service provider), ad platforms, and analytics tools — so data flows consistently across your tech stack. This creates a unified view of your customers and allows for smarter segmentation, retargeting, and attribution.
For the most powerful setup, use a platform like Opensend that specializes in identity resolution and cross-device tracking. Opensend plugs into your marketing stack and uses a proprietary identity graph to match anonymous users to known profiles, even if they haven’t logged in.
Once implemented, you can:
Cross-device tracking becomes a growth engine when it’s connected to the rest of your marketing. With Opensend, setup is fast, scalable, and designed for real-world impact.
Cross-device tracking gives growth marketers a serious advantage — a full view of the customer journey, better attribution, smarter retargeting, and the ability to personalize at scale.
Whether you're recovering abandoned carts, re-engaging inactive users, or optimizing your acquisition channels, cross-device visibility helps you do it all with greater accuracy and impact. And with a platform like Opensend, it’s easier than ever to connect those data points, identify users in real time, and turn fragmented sessions into clear, actionable journeys.
Ready to unlock cross-device tracking for your business? Start your free trial or book a demo with Opensend, and see how identity-powered marketing can drive smarter growth from the traffic you already have.
Sources:
What is deterministic/probabilistic data? | TechTarget
24+ Marketing Attribution Statistics You Need to Know in 2021 | Ruler Analytics
How to Collect First-Party Data | WebFX
The Keys to Abandoned Cart Recovery and Reducing Lost Sales | BigCommerce
.svg)
