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Expo Observe
A library that collects app performance metrics and dispatches them to EAS Observe.
EAS Observe is in Open Beta. The first 10,000 monthly active users are free. For higher usage, contact sales@expo.dev.
expo-observe is a library that collects performance metrics from your app and dispatches them to EAS Observe, a performance monitoring service from Expo, or to your preferred OpenTelemetry (OTEL)-compliant backend. It measures real-world startup performance, such as Time to First Render (TTR) and Time to Interactive (TTI), from apps running in production.
expo-observeis not available in Expo Go. To use it, create a development build.
Installation
- npx expo install expo-observeIf you are installing this in an existing React Native app, make sure to install expo in your project.
Configuration
In release builds, installing the expo-observe library is all that is needed to configure the library to start sending startup metrics (though you will need to follow the usage instructions below to call AppMetrics.markInteractive to track TTI). The library will not dispatch events in debug builds, but you can change this and other config options such as sample rate and environment name with the AppMetrics.configure({}) call. For all available options, see the EAS Observe configuration guide.
Usage
On SDK 55, wrap your root layout with AppMetricsRoot to measure Time to First Render automatically. Then, call AppMetrics.markInteractive when your app is ready for user interaction to record Time to Interactive:
import { AppMetrics, AppMetricsRoot } from 'expo-observe'; import { Stack } from 'expo-router'; import { useEffect } from 'react'; function RootLayout() { useEffect(() => { // Call markInteractive() after any initialization work behind the // splash screen completes. AppMetrics.markInteractive(); }, []); return <Stack />; } export default AppMetricsRoot.wrap(RootLayout);
For step-by-step instructions, including how to handle apps with multiple entry screens, see the EAS Observe Get started guide.
User-defined events and the navigation integrations require SDK 56 and later.
API
import { AppMetrics, AppMetricsRoot } from 'expo-observe';
Component
Type: React.Element<{
children: ReactNode
}>
A root component that automatically marks the first render.
Wrap your app's root component with this to measure time to first render
without manually calling AppMetrics.markFirstRender().
Interfaces
| Parameter | Type | Description |
|---|---|---|
| config | Config | Observability settings to apply. |
Configures how observability events are collected and dispatched at runtime, such as the environment label, dispatching behavior, and sampling.
voidExample
import Observe from 'expo-observe'; Observe.configure({ environment: 'production', dispatchingEnabled: true, });
Dispatches pending events to the server immediately.
Events are dispatched automatically when the app moves to the background. On Android, a background worker dispatches events once network connectivity is available. On iOS, dispatching happens when the app resigns active state or is about to terminate. Call this method to flush events manually, for example, during testing or to ensure events are sent before a specific point.
Promise<void>A promise that resolves when the pending events have been dispatched.
Example
import Observe from 'expo-observe'; await Observe.dispatchEvents();
| Property | Type | Description |
|---|---|---|
| category | string | - |
| name | string | - |
| params(optional) | Record<string, unknown> | - |
| routeName(optional) | string | - |
| sessionId | string | - |
| timestamp | string | - |
| value | number | - |
Types
| Property | Type | Description |
|---|---|---|
| dispatchInDebug(optional) | boolean | Whether to dispatch metrics that were collected in a debug build of the host app. When Has no effect on release builds. If Default: false |
| dispatchingEnabled(optional) | boolean | Whether to dispatch observability events to the server. When Default: true |
| environment(optional) | string | The environment for observability events Default: process.env.NODE_ENV |
| sampleRate(optional) | number | Fraction of installations that should dispatch metrics, in The decision is deterministic per installation — a device is either permanently in-sample or out-of-sample for a given rate, so the choice is stable across app launches. Interaction with
Default: undefined - metrics from all devices are sent |
| Property | Type | Description |
|---|---|---|
| params(optional) | Record<string, unknown> | Custom parameters to attach to the metric. |
| routeName(optional) | string | Name of the route associated with the metric. Some metrics populate this with a sensible default when omitted — for example, the TTI metric falls back to the initial route name detected from the router. |