Real User Monitoring

Last9 Real User Monitoring (RUM) captures real user experience data from web and mobile applications. Each SDK instruments sessions, views, network requests, unhandled errors, and resource metrics (plus ANRs on Android), then exports spans and logs to Last9 over OTLP/HTTP.

Supported platforms

Web JavaScript SDK. Core Web Vitals, JS errors, fetch/XHR instrumentation, session tracking. Works with React, Angular, Vue, Next.js.

Android / Kotlin Kotlin SDK. OkHttp interceptor, activity lifecycle, ANR detection, resource sampling.

iOS / Swift Swift SDK. URLProtocol instrumentation, UIKit/SwiftUI view tracking, crash capture.

React Native Bridges native Android + iOS SDKs. fetch/XHR instrumentation, React Navigation integration.

Flutter Dart plugin over native Android + iOS SDKs. HttpClient override, NavigatorObserver.

What gets captured

All SDKs auto-instrument the same signals:

Sessions — rolling session IDs with idle + max-duration expiry. Session ID is propagated on every span and log.
Views / page loads — screen transitions tracked as spans. Auto-tracked via SPA route changes (web), activity lifecycle (Android), UIKit/SwiftUI hooks (iOS), React Navigation (React Native), or NavigatorObserver (Flutter). Manual startView(name) is available on every platform.
Network — HTTP requests captured with URL, method, status, duration, request/response sizes. Traceparent header is injected so spans link to backend traces.
Errors — unhandled JS exceptions, promise rejections, native crashes, and Flutter framework errors. ANR detection is Android-only. Manual captureError(e, context) is available on every platform.
Core Web Vitals (web) — LCP, FCP, CLS, INP, TTFB.
Resources (mobile) — periodic memory and CPU samples (configurable interval, default 30s).
Custom events + attributes — addEvent, spanAttributes, and identify for user context.

Distribution

SDKs are distributed from Last9’s CDN:

Platform	Stable version	Artifact	Stable CDN root	Versioned CDN root
Web	`2.5.1`	UMD script	`https://cdn.last9.io/rum-sdk/builds/stable/v2/`	`https://cdn.last9.io/rum-sdk/builds/2.5.1/`
Android	`0.8.0`	AAR + POM	`https://cdn.last9.io/rum-sdk/android/builds/stable/v0/`	`https://cdn.last9.io/rum-sdk/android/maven/io/last9/rum-android/0.8.0/`
iOS	`0.8.0`	CocoaPods podspec + SPM XCFramework	`https://cdn.last9.io/rum-sdk/ios/builds/stable/v0/`	`https://cdn.last9.io/rum-sdk/ios/builds/0.8.0/`
React Native	`0.8.0`	npm tarball	`https://cdn.last9.io/rum-sdk/react-native/builds/stable/v0/`	`https://cdn.last9.io/rum-sdk/react-native/builds/0.8.0/`
Flutter	`0.8.0`	tar.gz package	`https://cdn.last9.io/rum-sdk/flutter/builds/stable/v0/`	`https://cdn.last9.io/rum-sdk/flutter/builds/0.8.0/`

Stable channels are major-version pinned: Web uses v2; mobile SDKs use v0. Mobile staging builds use the -alpha suffix and explicit versioned URLs.

Latest stable changes

Web 2.5.1 improves error normalization for non-Error throws and promise rejections, including strings, primitives, and plain objects.
Mobile 0.8.0 changes the ingestion Client-ID header to an SDK-generated per-install UUID instead of serviceName, preventing all devices for an app from sharing the same ingestion rate-limit bucket.
Mobile 0.7.x adds network waterfall child spans for dns, tcp_connect, tls_handshake, and ttfb, plus stronger unknown-error type handling.
Mobile 0.6.x adds view.ttfd to measure response-to-render latency on data-driven screens.

Next steps

Pick your platform:

Once data is flowing, explore it in Discover > Applications — performance, errors, sessions, and session correlation with backend traces. To turn RUM signals into alerts (HTTP error rates, p95 latency, crashes, ANRs), see Alerting on RUM Metrics.

Troubleshooting

Please get in touch with us on Discord or Email if you have any questions.