Session Replay (Web): Watch playbacks of user digital experiences

Overview

Mixpanel Session Replay is the fastest way to understand the whole picture about your customers and make better product decisions, by combining quantitative and qualitative user insights.

When digging into customer journeys in Mixpanel’s analytics, you can understand “where do customers drop-off?” And now, Mixpanel Session Replay enables you to quickly follow-up with, “why do customers drop off?”

Implementation

Session Replay is not enabled by default; enabling the feature requires instrumentation beyond the standard Mixpanel instrumentation. However, in most cases, implementation is extremely simple, only requiring a single line of code to be changed. Our documentation on how to implement Session Replay can be found here.

Replays sent via your implementation will only be viewable in the project they were ingested in and will not be available to other projects in your org.

Before you enable Session Replay for a large audience, we recommend testing in a demo project, and starting in production with smaller sets of users or accounts, so that you can monitor performance and ensure your privacy rules align with company policies.

FAQ

Is Session Replay available for mobile?

As of today, Session Replay is available for web-based applications (including mobile web) on the Enterprise Plan and closed Alpha testing for native iOS apps. Android Alpha testing is expected in early 2025.

For any questions about early mobile access, please reach out to your Account Manager.

Can I prevent Session Replay from recording sensitive content?

By default, all on-screen text elements are masked in replays. Additionally, you can customize how you initialize our SDK to fully control (1) where to record and (2) whom to record. For more details, please see our implementation docs.

How long are replays stored?

30 days.

How can I estimate how many replays I’ll have?

If you already use Mixpanel, the simplest way to estimate the amount of replays is to use a proxy metric for how many page loads you have. If you use timeout based query sessions, Total Session Start events in the Insights report could be a good estimate.

Then, when you enable Session Replay, use that metric and the sampling percentage to determine how many replays will be sent.

Am I able to sample our session replay collection rate?

Yes, you can configure the percentage of total replays that our SDK will capture with one line of code in your SDK implementation.

This out-of-the-box sampling method is random sampling: your SDK will decide randomly whether the currently SDK instance load falls into the sample or not. We recommend starting at 1% and increasing from there. If you expect low traffic, you can increase the starting sampling percentage.

If you’re still unsure about what sampling percentage to use, you can use our automatically generated Session Start events to estimate how many recordings you’ll be ingesting, and base the sampling off that.

If instead of random sampling, you want to use conditional logic to control which sessions to record, then your application code can derive its own yes/no decision, and then force a session recording to start after SDK initialization by calling mixpanel.start_session_recording().

If you want to only record certain parts of a single-page application with no new mixpanel.init calls, you can also use our Start / Stop methods.

Why does it say the player failed to load?

In order to maintain a high standard of security, Mixpanel runs your session replays in an isolated domain through an iframe. Sometimes, this domain may be blocked by an ad blocker or certain browser settings. Please try disabling any ad blockers.

For extensions like uBlock, you can navigate to “My Filters” in the extension settings and paste the following custom filter:

@@||mxpnl.com^$domain=mxpnl.com

Why can’t I view Replays from my Insights or Funnels chart?

Mixpanel looks for the $mp_replay_id property on your events in order to determine which replay it belongs to. If you have instrumented both Replays and Events using the Mixpanel JavaScript SDK, the $mp_replay_id will automatically be added to events sent by the SDK.

For CDP implementations, look below for instructions on how to configure the SDKs together. To get the relevant Session Replay properties from the SDK, use mixpanel.get_session_recording_properties(). See documentation.

How does Session Replay affect my website’s performance?

Mixpanel leverages the open-source library, rrweb, to power Session Replay. Both rrweb and Mixpanel are designed with the highest standards of performance in mind.

How the SDK works on your site – the gist:

Initial Snapshot: When recording starts, rrweb takes a snapshot of the entire webpage’s structure (the DOM), assigning unique IDs to each element for change tracking.
Change Detection: Asynchronously monitors any changes that occur to the DOM using MutationObserver, minimizing work so that we don’t need to keep taking full snapshots.
User Interactions: Listens for actions like clicks and mouse movements and throttles any high frequency events.
Collection & Delivery: Mixpanel collects the recording data and sends it to our servers in batches every 10 seconds.
Optimized Compression: Before sending, Mixpanel will compress the payload using the asynchronous CompressionStream API. This will optimize bandwidth while not blocking the UI thread.

We’ve tested the SDK extensively and it generally has minimal impact on how your website performs. The initial snapshot takes a bit of work, and naturally, more complex and interactive pages generate more data for rrweb and Mixpanel to handle. So, it’s always a good practice to do some performance testing after you’ve implemented Session Replay, just to be sure everything’s running smoothly.

How do Session Replays work when navigating between pages that are full page loads?

If your web application relies on full page loads (where the entire page is reloaded when navigating from one page to another), a new Session Replay recording $mp_replay_id will be created when navigating to each page. This occurs because the Mixpanel instance is reloaded again when navigating between pages.

Can I use Session Replay with a CDP?

Yes. You can use Session Replay with CDPs like Segment and mParticle.

In order to use Session Replay, your app must include the Mixpanel SDK. Consult the quickstart to ensure you have the Mixpanel SDK installed, and the setup guide to make sure you have Session Replay enabled.

Once you have included the Mixpanel SDK in your app add the following code snippets in order to connect your CDP’s data stream with Mixpanel’s Session Replay.

Segment: Analytics.js

By adding middleware to Segment’s SDK we can ensure that all event calls include the session replay properties. We can also ensure that any identify calls are also passed to Mixpanel.

// Middleware to add Mixpanel's session recording properties to Segment events
analytics.addSourceMiddleware(({ payload, next, integrations }) => {
	if (payload.obj.type === 'track' || payload.obj.type === 'page') {
		if (window.mixpanel) {
			const segmentDeviceId = payload.obj.anonymousId;
			// -------------------------------------------
			// Comment out one of the below mixpanel.register methods depending on your ID Management Version
			// Original ID Merge
			mixpanel.register({ $device_id: segmentDeviceId, distinct_id : segmentDeviceId });
			// Simplified ID Merge
			mixpanel.register({ $device_id: segmentDeviceId, distinct_id : "$device:"+segmentDeviceId }); 
			// -------------------------------------------	
			const sessionReplayProperties = mixpanel.get_session_recording_properties();
			payload.obj.properties = {
				...payload.obj.properties,
				...sessionReplayProperties
			};
		}
	}
	if (payload.obj.type === 'identify') {
		if (window.mixpanel) {
			const userId = payload.obj.userId;
			mixpanel.identify(userId);
		}
	}
	next(payload);
});

mParticle: Web SDK

mParticle’s Web SDK has a .getDeviceId() method which can be used to retrieve the device_id. In the following example, we use this method to bind mParticle’s device_id to Mixpanel’s device_id, as wall as patching logEvent and logPageView to include session replay properties on all mParticle events. This configuration assumes you are forwarding web requests server side in the connection settings.

mixpanel.init('MIXPANEL-PROJECT-TOKEN', {
	record_sessions_percent: 10,
	loaded: function (mixpanel) {
		window.mParticle.ready(function() {
			const mParticle_device_id = mParticle.getDeviceId();
			if (mParticle_device_id) {
				mixpanel.register({ $device_id: mParticle_device_id, distinct_id : "$device:"+mParticle_device_id });
			}
 
			// Patch logEvent and logPageView to include sessionReplayProperties
			const originalLogEvent = mParticle.logEvent;
			mParticle.logEvent = function (eventName, eventType, eventAttributes, flags, opts) {
				const sessionReplayProperties = mixpanel.get_session_recording_properties();
				eventAttributes = {
					...eventAttributes,
					...sessionReplayProperties,
				};
				originalLogEvent(eventName, eventType, eventAttributes, flags, opts);
			};
			const originalLogPageView = mParticle.logPageView;
			mParticle.logPageView = function (eventName, eventAttributes, flags, opts) {
				const sessionReplayProperties = mixpanel.get_session_recording_properties();
				eventAttributes = {
					...eventAttributes,
					...sessionReplayProperties,
				};
				originalLogPageView(eventName, eventAttributes, flags, opts);
			};
		});
	}
});

Rudderstack: Cloud Mode

Rudderstack’s Javascript SDK has a .getAnonymousId() method which can be used to retrieve the device_id. In the following example, we use this method to bind Rudderstack’s anonymousId to Mixpanel’s device_id, as well as patching track and page event methods to include session replay properties on every Rudderstack event.

mixpanel.init('MIXPANEL-PROJECT-TOKEN', {
  record_sessions_percent: 10,
  loaded: function (mixpanel) {
    window.rudderanalytics.ready(function() {
      const rudderAnonymousId = rudderanalytics.getAnonymousId();
      if (rudderAnonymousId) {
	mixpanel.register({ $device_id: rudderAnonymousId, distinct_id : "$device:"+rudderAnonymousId });
      }
 
      // Patch track method to include sessionReplayProperties
      const originalTrack = rudderanalytics.track;
      rudderanalytics.track = function (eventName, eventProperties, options, callback) {
        const sessionReplayProperties = mixpanel.get_session_recording_properties();
        eventProperties = {
          ...eventProperties,
          ...sessionReplayProperties,
        };
        originalTrack(eventName, eventProperties, options, callback);
      };
 
      // Patch page method to include sessionReplayProperties
      const originalPage = rudderanalytics.page;
      rudderanalytics.page = function (category, name, properties, options, callback) {
        const sessionReplayProperties = mixpanel.get_session_recording_properties();
        properties = {
          ...properties,
          ...sessionReplayProperties,
        };
        originalPage(category, name, properties, options, callback);
      };
    });
  }
});

Google Tag Manager (GTM)

You can use session replay with Google Tag Manager. First, make sure you have the Mixpanel GTM Template installed in your workspace.

Once that is added, you can add a new Mixpanel tag to your workspace which turns on Session Replay by following these instructions:

Add a new tag, and choose the Mixpanel tag type.
For Project Token fill in your Mixpanel project’s token
For Tag Type choose init from the dropdown
For Initialization choose Set Options Manually
In the Option key / Option value dropdown, ensure you choose record_sessions_percent and the value should be a number between 1 and 100.
This is also where you can configure other Session Replay options like record_block_class etc…
For the Triggering section, you’ll want to choose something early in the GTM lifecycle; typically this is Initialization - All Pages or Consent Initialization - All Pages to ensure that Session Replay starts recording as soon as the GTM container is initialized.
Save + Deploy this template to your website and you should be up and going with session replay

Here’s a screenshot of a working session replay tag for a visual comparison:

Session Replay iOS (Alpha)

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