Readable Kotlin crash stack traces for Firebase Crashlytics, Sentry, and Bugsnag.

Kotlin Multiplatform apps crash in shared Kotlin code on iOS, but the reports shown in major crash-reporting vendors are unreadable — raw kfun:-mangled symbols, no source file/line. KotlinTrace fixes the readability layer client-side, with no backend: one call at startup, and the same crash shows demangled function names and (File.kt:line) locations.

Works with the crash reporter you already use — Firebase Crashlytics, Sentry, or Bugsnag. No new backend, no vendor lock-in.

Before (what vendors normally receive):

IllegalStateException: Uncaught Kotlin exception
    at 0   iosApp   0x1020e88e7   kfun:kotlin.Exception#<init>(kotlin/String?;kotlin.Throwable?){} + 119
    at 1   iosApp   0x1020d3273   kfun:dev.kotlintrace.sample.CrashBot#crash(){}kotlin.Throwable + 159
    ... and 38 more stack frames

After (with KotlinTrace):

IllegalStateException: Uncaught Kotlin exception
    at CrashBot.crash (CrashBot.kt:33)
    at crashOnBackgroundThread$crashTrampoline (MainKt.kt:21)

KotlinTrace is iOS-only (Kotlin/Native). Add one dependency per vendor you use, call one function at startup — done.

// shared module build.gradle.kts — commonMain.dependencies
implementation("io.github.mahdimerhi:kotlintrace-crashlytics:0.1.0")  // Firebase Crashlytics
implementation("io.github.mahdimerhi:kotlintrace-sentry:0.1.0")       // Sentry
implementation("io.github.mahdimerhi:kotlintrace-bugsnag:0.1.0")      // Bugsnag

Add only the modules whose SDKs you already link. All three work side by side if you use multiple reporters.

Install the hook before any Kotlin code can crash — the earlier, the better. One call is enough; repeated calls and multi-adapter installs merge safely.

// Shared Kotlin, e.g. called from your SwiftUI App.init()
fun setupCrashReporting() {
    KotlinTrace.installCrashlytics() // or installSentry() / installBugsnag()
}

From Swift, call it through a tiny wrapper in your shared module:

@main
struct MyApp: App {
    init() {
        setupCrashReporting() // → KotlinTrace.installCrashlytics()
    }
}

Crash the app in shared Kotlin code (uncaught exception), relaunch, and check your Crashlytics / Sentry / Bugsnag dashboard: the event now shows demangled Kotlin functions with (File.kt:line).

KotlinTrace.installSentry(
    demangle = true,                      // default: true
    includeKotlinSourceLocation = true,   // default: true
)
// same parameters on installCrashlytics() and installBugsnag()

• Client-side rewrite. KotlinTrace rewrites the Kotlin stack-trace frames before the event reaches your vendor's native crash API. No backend involved.
• One clean event per crash. It reports once, flushes the transport, then exits — so the OS-native abort (which would add a second, mangled event) never fires.
• Friendly noise dropped. Runtime bootstrap frames (K/N runtime init, trampolines) and non-Kotlin bridge frames are removed from the report.
• (File.kt:line) resolves via the K/N runtime's DWARF capabilities on device and simulator. Release builds without debug info fall back to function names only.

The core engine (:kotlintrace) holds the uncaught-exception hook + demangler; the adapters wire the vendors. The core's low-level API (KotlinTrace.install(...) + KotlinTraceOptions) is there if you want to write your own sink — most apps just use the install*() extensions above.

• iOS app (Kotlin/Native targets: iosArm64, iosSimulatorArm64, iosX64)
• Kotlin 2.x Multiplatform project
• The vendor SDK linked in the app as usual (Firebase Crashlytics / sentry-cocoa / bugsnag-cocoa)
• Sentry apps: disable Sentry's own crash handler so it doesn't add a duplicate mangled native event (options.enableCrashHandler = false)

• PROJECT.md — architecture, roadmap, integration details
• TODO.md — release checklist

Apache-2.0 — see LICENSE. Copyright (c) 2026 Mahdi Merhi.