Cross-platform instrumentation vs. separate platform instrumentation

Amplitude customers often ask if they should use the same API Key for the iOS and Android versions of the same app, or if they should tie web and mobile data together. The answer depends on the kind of apps you have and the kind of analyses you want to do.

Sometimes, an app behaves differently on each individual platform—Android, iOS, and web—so your top priority should be to analyze how each one performs on its own. Other times, understanding a user's behavior irrespective of the platform is the top priority: you know your users can come from any platform, and you're more interested in a user's actions than the platform they were on when they took those actions.

When to do a cross-platform instrumentation

Here are some situations when it makes sense to do a cross-platform instrumentation:

• You expect frequent user crossover between platforms.
• You want to analyze user behavior across platforms as a key focus for your company. (This requires you to collect user IDs.)
• You have experience using the same API key in another analytics product.
• You've read and understood the advantages of using the same API keys (found below).

There are two primary advantages to this approach: You can see totals across all platforms in a single unified view; and you can create funnels or retention charts that analyze user behavior across platforms.

When to do a separate platform instrumentation

Sometimes it makes more sense to do a separate platform instrumentation. Here are a couple examples:

• Your app acts as a standalone on each platform, and user crossover analysis isn't important.
• Your goal is to understand how users are engaging within each platform.

Additionally, there are several advantages to consider:

• Platform differences: Even if your app has the same primary functions on iOS and Android, there are slight differences when it comes to how certain actions are tracked (for example, asking for permissions); these may warrant separation. Any slight differences in the apps themselves (like showing different landing/tutorial screens) may be easier to manage if separated as well.
• Different update cycles: Instrumentation changes happen all the time, and it's rare for app updates to go live on the same day. This means data and possibly new events from a new version on a certain platform could get mixed in with data and old events on the old version, which would pollute the dashboard and take focus away from the important metrics.
• Difficulty finding errors: Having events from multiple platforms on the same dashboard makes it more difficult to spot errors and bugs in instrumentation and make the necessary fixes.
• Web and mobile are VERY different: The experiences on web and mobile differ, and the kinds of events you probably want to track may be very different as well.