Firebase Crashlytics vs Sentry Comparison

// Firebase Crashlytics - Android (Kotlin) setup and non-fatal logging
// build.gradle.kts (app)
// plugins { id("com.google.gms.google-services"); id("com.google.firebase.crashlytics") }
// dependencies { implementation(platform("com.google.firebase:firebase-bom:34.19.0"))
//                implementation("com.google.firebase:firebase-crashlytics") }

import com.google.firebase.Firebase
import com.google.firebase.crashlytics.crashlytics
import com.google.firebase.crashlytics.setCustomKeys

class CheckoutViewModel {

    private val crashlytics = Firebase.crashlytics

    fun onPaymentStarted(orderId: String, amount: Double) {
        // Breadcrumb: lets you see which step you were on if a crash occurs
        crashlytics.log("payment_started order=$orderId amount=$amount")
        crashlytics.setCustomKeys {
            key("order_id", orderId)
            key("payment_amount", amount)
            key("user_tier", "premium")
        }
    }

    fun onPaymentFailed(error: Throwable, orderId: String) {
        // Record the error without crashing the app (non-fatal)
        crashlytics.setCustomKey("order_id", orderId)
        crashlytics.recordException(error)
    }

    fun identifyUser(userId: String) {
        crashlytics.setUserId(userId)
    }
}

// AndroidManifest.xml: firebase_crashlytics_collection_enabled=false (enable after consent)
// Runtime: Firebase.crashlytics.setCrashlyticsCollectionEnabled(true)

// Sentry - iOS (Swift): error + performance + session replay in one SDK
// Package.swift / SPM: https://github.com/getsentry/sentry-cocoa

import Sentry

func configureSentry() {
    SentrySDK.start { options in
        options.dsn = "https://<public-key>@o<org-id>.ingest.sentry.io/<project-id>"
        options.debug = false

        // Performance tracing
        options.tracesSampleRate = 0.2

        // UI Profiling (sentry-cocoa 9.x): tied to the trace lifecycle
        options.configureProfiling = {
            $0.lifecycle = .trace
            $0.sessionSampleRate = 1.0
        }

        // Session Replay: records the screen flow leading up to a crash
        options.sessionReplay.onErrorSampleRate = 1.0
        options.sessionReplay.sessionSampleRate = 0.1

        // Screenshot + view hierarchy at the moment of the error
        options.attachScreenshot = true
        options.attachViewHierarchy = true
    }
}

// Breadcrumb + custom context + non-fatal capture
func onPaymentFailed(_ error: Error, orderId: String) {
    let crumb = Breadcrumb(level: .error, category: "payment")
    crumb.message = "payment_failed order=\(orderId)"
    SentrySDK.addBreadcrumb(crumb)

    SentrySDK.configureScope { scope in
        scope.setTag(value: orderId, key: "order_id")
        scope.setUser(User(userId: "u_123"))
    }
    SentrySDK.capture(error: error)
}

// Automatic dSYM upload (Xcode Run Script Build Phase):
// sentry-cli debug-files upload --include-sources "$DWARF_DSYM_FOLDER_PATH"