It uses an internal queue to make calls fast and non-blocking. It also batches requests and flushes asynchronously, making it perfect to use in any part of your mobile app.

Installation

The best way to install the PostHog Android library is with a build system like Gradle. This ensures you can easily upgrade to the latest versions.

All you need to do is add the posthog-android module to your App's build.gradle or build.gradle.kts:

dependencies {
  implementation 'com.posthog:posthog-android:3.+'
}

dependencies {
  implementation("com.posthog:posthog-android:3.+")
}

Configuration

The best place to initialize the client is in your Application subclass.

import android.app.Application
import com.posthog.android.PostHogAndroid
import com.posthog.android.PostHogAndroidConfig

class SampleApp : Application() {

    companion object {
        const val POSTHOG_API_KEY = "<ph_project_token>"
        // usually 'https://us.i.posthog.com' or 'https://eu.i.posthog.com'
        const val POSTHOG_HOST = "https://us.i.posthog.com"
    }

    override fun onCreate() {
        super.onCreate()

        val config = PostHogAndroidConfig(
            apiKey = POSTHOG_API_KEY,
            host = POSTHOG_HOST 
        )
        PostHogAndroid.setup(this, config)
    }
}

Capturing events

You can send custom events using capture:

import com.posthog.PostHog

PostHog.capture(event = "user_signed_up")

Tip: We recommend using a [object] [verb] format for your event names, where [object] is the entity that the behavior relates to, and [verb] is the behavior itself. For example, project created, user signed up, or invite sent.

Setting event properties

Optionally, you can include additional information with the event by including a properties object:

import com.posthog.PostHog

PostHog.capture(
    event = "user_signed_up",
    properties = mapOf(
        "login_type" to "email",
        "is_free_trial" to true
    )
)

Autocapture

PostHog autocapture automatically tracks the following events for you:

• Application Opened - when the app is opened from a closed state or when the app comes to the foreground. (e.g. from the app switcher)
• Deep Link Opened - when the app is opened from a deep link.
• Application Backgrounded - when the app is sent to the background by the user.
• Application Installed - when the app is installed.
• Application Updated - when the app is updated.
• $screen - when the user navigates. (if using android.app.Activity)
• $exception - when uncaught exception autocapture is enabled. To use this, enable Android error tracking and exception autocapture in the SDK config.

Capturing screen views

With captureScreenViews = true, PostHog will try to record all screen changes automatically.

The screenTitle will be the <activity>'s android:label, if not set it'll fallback to the <application>'s android:label or the <activity>'s android:name.

<activity
    android:name="com.example.app.ChildActivity"
    android:label="@string/title_child_activity"
    ...
</activity>

If you want to manually send a new screen capture event, use the screen function.

This function requires a screenTitle. You may also pass in an optional properties object.

import com.posthog.PostHog

PostHog.screen(
    screenTitle = "Dashboard",
    properties = mapOf(
        "background" to "blue",
        "hero" to "superhog"
    )
)

Identifying users

We highly recommend reading our section on Identifying users to better understand how to correctly use this method.

Using identify, you can associate events with specific users. This enables you to gain full insights as to how they're using your product across different sessions, devices, and platforms.

An identify call has the following arguments:

• distinctId: Required. A unique identifier for your user. Typically either their email or database ID.
• userProperties: Optional. A dictionary with key:value pairs to set the person properties
• userPropertiesSetOnce: Optional. Similar to userProperties. See the difference between userProperties and userPropertiesSetOnce

import com.posthog.PostHog

PostHog.identify(
    distinctId = distinctID,
    userProperties = mapOf(
        "name" to "Max Hedgehog", 
        "email" to "max@hedgehogmail.com"
    ),
    userPropertiesSetOnce = mapOf(
        "date_of_first_log_in" to "2024-03-01"
    ),
)

You should call identify as soon as you're able to. Typically, this is after your user logs in. This ensures that events sent during your user's sessions are correctly associated with them.

When you call identify, all previously tracked anonymous events will be linked to the user.

Get the current user's distinct ID

You may find it helpful to get the current user's distinct ID. For example, to check whether you've already called identify for a user or not.

To do this, call distinctId(). This returns either the ID automatically generated by PostHog or the ID that has been passed by a call to identify().

Alias

Sometimes, you want to assign multiple distinct IDs to a single user. This is helpful when your primary distinct ID is inaccessible. For example, if a distinct ID used on the frontend is not available in your backend.

In this case, you can use alias to assign another distinct ID to the same user.

/**
 * Create an alias for the current user.
 */
PostHog.alias("distinct_id")

We strongly recommend reading our docs on alias to best understand how to correctly use this method.

Anonymous and identified events

PostHog captures two types of events: anonymous and identified

Identified events enable you to attribute events to specific users, and attach person properties. They're best suited for logged-in users.

Scenarios where you want to capture identified events are:

• Tracking logged-in users in B2B and B2C SaaS apps
• Doing user segmented product analysis
• Growth and marketing teams wanting to analyze the complete conversion lifecycle

Anonymous events are events without individually identifiable data. They're best suited for web analytics or apps where users aren't logged in.

Scenarios where you want to capture anonymous events are:

• Tracking a marketing website
• Content-focused sites
• B2C apps where users don't sign up or log in

Under the hood, the key difference between identified and anonymous events is that for identified events we create a person profile for the user, whereas for anonymous events we do not.

Important: Due to the reduced cost of processing them, anonymous events can be up to 4x cheaper than identified ones, so we recommended you only capture identified events when needed.

How to capture anonymous events

The Android SDK captures anonymous events by default. However, this may change depending on your personProfiles config when initializing PostHog:

1. personProfiles = PersonProfiles.IDENTIFIED_ONLY (recommended) (default) - Anonymous events are captured by default. PostHog only captures identified events for users where person profiles have already been created.

2. personProfiles = PersonProfiles.ALWAYS - Capture identified events for all events.

3. personProfiles = PersonProfiles.NEVER - Capture anonymous events for all events.

For example:

val config = PostHogAndroidConfig(
   apiKey = POSTHOG_API_KEY,
   host = POSTHOG_HOST,
).apply {
   personProfiles = PersonProfiles.IDENTIFIED_ONLY
}

How to capture identified events

If you've set the personProfiles config to IDENTIFIED_ONLY (the default option), anonymous events are captured by default. Then, to capture identified events, call any of the following functions:

• identify()
• alias()
• group()

When you call any of these functions, it creates a person profile for the user. Once this profile is created, all subsequent events for this user will be captured as identified events.

Alternatively, you can set personProfiles to ALWAYS to capture identified events by default.

Setting person properties

To set properties on your users via an event, you can leverage the event properties userProperties and userPropertiesSetOnce.

When capturing an event, you can pass a property called userProperties as an event property, and specify its value to be an object with properties to be set on the user that will be associated with the user who triggered the event.

import com.posthog.PostHog

PostHog.capture(
    event = "button_b_clicked",
    properties = mapOf("color" to "blue"),
    userProperties = mapOf(
        "string" to "value1",
        "integer" to 2
    )
)

userPropertiesSetOnce works just like userProperties, except that it will only set the property if the user doesn't already have that property set.

import com.posthog.PostHog

PostHog.capture(
    event = "button_b_clicked",
    properties = mapOf("color" to "blue"),
    userPropertiesSetOnce = mapOf(
        "string" to "value1",
        "integer" to 2
    )
)

Super Properties

Super Properties are properties associated with events that are set once and then sent with every capture call, be it a $screen, or anything else.

They are set using PostHog.register, which takes a key and value, and they persist across sessions.

For example, take a look at the following call:

import com.posthog.PostHog

PostHog.register("team_id", 22)

The call above ensures that every event sent by the user will include "team_id": 22. This way, if you filtered events by property using team_id = 22, it would display all events captured on that user after the PostHog.register call, since they all include the specified Super Property.

However, please note that this does not store properties against the User, only against their events. To store properties against the User object, you should use PostHog.identify. More information on this can be found on the Sending User Information section.

Removing stored Super Properties

Super Properties are persisted across sessions so you have to explicitly remove them if they are no longer relevant. In order to stop sending a Super Property with events, you can use PostHog.unregister, like so:

import com.posthog.PostHog

PostHog.unregister("team_id")

This will remove the Super Property and subsequent events will not include it.

If you are doing this as part of a user logging out you can instead simply use PostHog.reset which takes care of clearing all stored Super Properties and more.

Opt out of data capture

You can completely opt-out users from data capture. To do this, there are two options:

1. Opt users out by default by setting optOut to true in your PostHog config:

val config = PostHogAndroidConfig(
    apiKey = <ph_project_token>,
    host = https://us.i.posthog.com 
)
config.optOut = true
PostHogAndroid.setup(this, config)

2. Opt users out on a per-person basis by calling optOut():

PostHog.optOut()

Similarly, you can opt users in:

PostHog.optIn()

To check if a user is opted out:

PostHog.isOptOut()

Flush

You can configure how many events queue before flushing with flushAt. Setting this to 1 will send events immediately and will use more battery. The default is 20.

You can also configure the flush interval with flushIntervalSeconds (default 30), after which queued events are sent regardless of how many have been gathered:

import com.posthog.android.PostHogAndroidConfig

val config = PostHogAndroidConfig(apiKey = POSTHOG_API_KEY, host = POSTHOG_HOST).apply {
    flushAt = 20
    flushIntervalSeconds = 30
}

You can also manually flush the queue to start sending events immediately instead of waiting for the next batch:

import com.posthog.PostHog

PostHog.flush()

Flushing is best-effort and asynchronous – it starts sending queued events in the background but doesn't wait for the request to finish, so it isn't a delivery guarantee.

Reset after logout

To reset the user's ID and anonymous ID, call reset. Usually you would do this right after the user logs out.

import com.posthog.PostHog

PostHog.reset()

Feature Flags

PostHog's feature flags enable you to safely deploy and roll back new features as well as target specific users and groups with them.

Boolean feature flags

import com.posthog.PostHog

if (PostHog.isFeatureEnabled("flag-key")) {
    // Do something differently for this user

    // Optional: fetch the payload
    val matchedFlagPayload = PostHog.getFeatureFlagPayload("flag-key")
}

Multivariate feature flags

import com.posthog.PostHog

if (PostHog.getFeatureFlag("flag-key") == "variant-key") { // replace 'variant-key' with the key of your variant
    // Do something differently for this user

    // Optional: fetch the payload
    val matchedFlagPayload = PostHog.getFeatureFlagPayload("flag-key")
}

Feature flag values and payloads together

If you need both the flag value and payload, use getFeatureFlagResult so both values come from the same evaluation result.

import com.posthog.PostHog

val result = PostHog.getFeatureFlagResult("flag-key")

if (result?.value == "variant-key") {
    val payload = result.payload
    // Do something with the variant and payload
}

You can also inspect all currently loaded feature flag results with PostHog.getAllFeatureFlags().

Ensuring flags are loaded before usage

Every time a user opens the app, we send a request in the background to fetch the feature flags that apply to that user. We store those flags in the storage.

This means that for most screens, the feature flags are available immediately – except for the first time a user visits.

To handle this, you can use the onFeatureFlags callback to wait for the feature flag request to finish:

import com.posthog.PostHog
import com.posthog.android.PostHogAndroidConfig
import com.posthog.PostHogOnFeatureFlags

// During SDK initialization
val config = PostHogAndroidConfig(apiKey = "<ph_project_token>").apply {
    onFeatureFlags = PostHogOnFeatureFlags {
        if (PostHog.isFeatureEnabled("flag-key")) {
            // do something
        }
    }
}

// And/or after the SDK is initialized
PostHog.reloadFeatureFlags {
    if (PostHog.isFeatureEnabled("flag-key")) {
        // do something
    }
}

Reloading feature flags

Feature flag values are cached. If something has changed with your user and you'd like to refetch their flag values, call:

import com.posthog.PostHog

PostHog.reloadFeatureFlags()

Tracking feature usage

To track when someone sees or interacts with a feature, use captureFeatureView and captureFeatureInteraction.

import com.posthog.PostHog

PostHog.captureFeatureView("flag-key", flagVariant = "variant-key")
PostHog.captureFeatureInteraction("flag-key", flagVariant = "variant-key")

Experiments (A/B tests)

Since experiments use feature flags, the code for running an experiment is very similar to the feature flags code:

import com.posthog.PostHog

if (PostHog.getFeatureFlag("experiment-feature-flag-key") == "variant-name") {
    // do something
}

It's also possible to run experiments without using feature flags.

Group analytics

Group analytics allows you to associate the events for that person's session with a group (e.g. teams, organizations, etc.). Read the Group Analytics guide for more information.

Note: This is a paid feature and is not available on the open-source or free cloud plan. Learn more on the pricing page.

• Associate the events for this session with a group

import com.posthog.PostHog

// organization is the group type, company_id_in_your_db is the group ID
PostHog.group(
    type = "company", 
    key = "company_id_in_your_db"
)

• Associate the events for this session with a group AND update the properties of that group

import com.posthog.PostHog

PostHog.group(
    type = "company", 
    key = "company_id_in_your_db",
    groupProperties = mapOf("name" to "Awesome Inc.")
)

The name is a special property which is used in the PostHog UI for the name of the group. If you don't specify a name property, the group ID will be used instead.

Error tracking

To set up error tracking in your project, follow the Android installation guide.

Logs

To set up logs in your Android app, follow the Android logs installation guide. The SDK exposes PostHog.logger.{trace,debug,info,warn,error,fatal} for sending structured records to PostHog Logs, with batching, offline persistence, and a rate cap built in.

Minimum version: com.posthog:posthog-android@3.46.0 or later.

Session replay

To set up session replay in your project, all you need to do is install the Android SDK, enable "Record user sessions" in your project settings and enable the sessionReplay option.

Surveys

To set up surveys, follow the additional installation instructions for Android. Surveys launched with popover presentation are automatically shown to users matching the display conditions you set up.

Offline behavior

The PostHog Android SDK will continue to capture events when the device is offline. The events are stored in a queue in the device's file storage and are flushed when the device is online.

• The queue has a maximum size defined by maxQueueSize in the configuration.
• When the queue is full, the oldest event is deleted first.
• The queue is flushed when the app is restarted and the device is online.
• When you call flush() while the device is offline, it aborts early and the events are not flushed.

Debug mode

If you're not seeing the expected events being captured, the feature flags being evaluated, surveys being shown, or session replay/error tracking behavior, you can enable debug mode to see what's happening.

You can enable debug mode by setting the debug option to true in the PostHogAndroidConfig object. This will enable verbose logs about the inner workings of the SDK.

val config = PostHogAndroidConfig(apiKey = POSTHOG_API_KEY, host = POSTHOG_HOST).apply {
    debug = true
    // ... other config options
}

All configuration options

When creating the PostHog client, pass a PostHogAndroidConfig. It inherits the core PostHogConfig options and adds Android-specific options.

import com.posthog.PersonProfiles
import com.posthog.android.PostHogAndroidConfig

val config = PostHogAndroidConfig(
    apiKey = POSTHOG_API_KEY,
    host = POSTHOG_HOST
).apply {
    captureApplicationLifecycleEvents = true
    captureScreenViews = true
    captureDeepLinks = true

    flushAt = 20
    maxQueueSize = 1000
    maxBatchSize = 50
    maxRetries = 3
    flushIntervalSeconds = 30

    debug = false
    optOut = false

    sendFeatureFlagEvent = true
    featureFlagCalledCacheSize = 1000
    preloadFeatureFlags = true
    evaluationContexts = listOf("production", "android", "mobile")

    setDefaultPersonProperties = true
    personProfiles = PersonProfiles.IDENTIFIED_ONLY
    reuseAnonymousId = false

    sessionReplay = false
    errorTrackingConfig.autoCapture = false
}

Android-specific options

Core options

Feature flag options

Product configuration objects

Event filtering with beforeSend

Use addBeforeSend to redact, modify, or drop events before they are queued. Return null to drop an event.

config.addBeforeSend { event ->
    event.properties?.remove("password")

    if (event.event == "internal_debug_event") {
        null
    } else {
        event
    }
}

FAQ

What Android API level is required?

The Android SDK supports Android API 23 and newer.

Do I need to declare permissions in the AndroidManifest.xml?

Usually, no. The SDK declares android.permission.INTERNET and android.permission.ACCESS_NETWORK_STATE, and Android's manifest merger adds them to your app. The SDK does not declare or require an Android Service.