TL;DR
- Error tracking captures crashes, exceptions, and ANRs with stack traces, breadcrumbs, and device context. It answers "what broke?" Tools: Crashlytics, Sentry, Bugsnag, Instabug.
- APM captures latency, throughput, database query time, API response time, and distributed traces across services. It answers "what's slow?" Tools: Datadog, New Relic, Dynatrace, AppDynamics.
- The line is blurring. Sentry now includes performance monitoring (traces, spans, transaction duration). Datadog now includes error tracking. Embrace bundles crash reporting with mobile specific performance metrics.
- For most mobile teams under 10 engineers, error tracking alone covers 90% of debugging needs. APM becomes necessary when your app depends on complex backend services and you need to trace a mobile timeout through API gateway to database query that caused it.
Where Drizz fits:
- Drizz is a pre release testing tool. It catches crashes and performance regressions on real devices in CI before build ships.
- It doesn't replace error tracking or APM in production. It reduces volume of issues that reach both.
What does error tracking do that APM doesn't?
Error tracking is focused on failures. Something broke, and you need to know what, where, and for how many users.
- Crash capture: unhandled exceptions, signal crashes (SIGSEGV, SIGABRT), and ANRs with full stack traces
- Error grouping: clusters identical crashes by fingerprinting stack trace so you see one issue with 500 occurrences, not 500 separate reports
- Device context: device model, OS version, available memory, battery state, network type at time of crash
- Breadcrumbs: sequential trail of user actions and system events (button taps, API calls, view transitions) leading up to failure
- Jira/Linear integration: auto creates tickets from crash alerts with context prefilled, routes to developer who owns file
- Release health: crash free rate per version, regressed crash detection, velocity alerts
Error tracking doesn't tell you why your checkout screen takes 4 seconds to load or that /api/cart endpoint is returning in 3.2 seconds because database query behind it is scanning full table. That's APM territory.
What does APM do that error tracking doesn't?
APM is focused on performance. The app isn't crashing, but it's slow, and you need to find where time goes.
- Distributed tracing: follows a single request from mobile app through API gateway, load balancer, backend service, and database, showing latency at each hop
- Transaction monitoring: measures how long each API call, screen render, or background task takes, aggregated across all users
- Database query analysis: identifies slow queries, N+1 patterns, and missing indexes that cause API latency
- Infrastructure correlation: links application slowness to CPU spikes, memory pressure, or network congestion on backend
- Real user monitoring (RUM): measures actual page/screen load times as experienced by users, segmented by device, OS, and geography
APM doesn't tell you that your app crashed with a NullPointerException in PaymentProcessor.processCard() on Samsung Galaxy S24 running Android 15, and it doesn't group that crash with 47 other occurrences on same device model. That's error tracking territory.
A thread on r/devops asking whether Sentry and Datadog fulfill same role surfaces practical distinction: Sentry catches crash and gives you line numbers to patch; Datadog shows you slow API endpoint and database query behind it. Teams running both report that they use Sentry 10x more often for mobile debugging because mobile problems are crashes and ANRs, not infrastructure bottlenecks.
Where do error tracking and APM overlap?
The distinction was clean five years ago. Today, tools have converged, and overlap creates confusion about what you're actually paying for.
Sentry: error tracking that added performance
Sentry started as an error tracker and added performance monitoring (traces, spans, transaction durations) in 2020. For mobile, this means you can see how long your API calls take, which screens render slowly, and where cold starts are bottlenecked.
The performance data is useful but not as deep as a dedicated APM: Sentry traces mobile app's outbound requests but doesn't instrument your backend services, database queries, or infrastructure. If slow API call is caused by a missing database index, Sentry shows you call took 3 seconds but doesn't tell you why.
For mobile teams that want basic performance visibility alongside crash reporting, Sentry's built in performance covers gap without buying a second tool. For teams with complex backend architectures, Sentry's performance is a starting point, not a replacement for Datadog or New Relic.
Engineers on r/devops looking for cheaper Datadog alternatives for APM frequently land on Sentry's performance monitoring as 80% solution: it traces outbound API calls and screen render times, which is enough to identify "this endpoint is slow" even if it can't tell you why database query behind it is slow.
Datadog: APM that added error tracking
Datadog started as infrastructure monitoring, added APM, then added error tracking and RUM. For mobile, Datadog RUM captures crashes, errors, session replays, and performance metrics in same dashboard as backend traces.
The advantage: if a mobile crash is caused by a 500 error from your API, and that 500 is caused by a timeout on a downstream microservice, Datadog traces full chain in one view. No tool switching between Crashlytics and a separate backend monitor.
The disadvantage: Datadog's mobile error tracking is less mature than Sentry's or Crashlytics', with crash grouping, breadcrumb depth, and Jira integration that are functional but not as refined. The pricing is enterprise level, making it impractical for small teams.
Embrace: mobile native observability that blurs line
Embrace bundles crash reporting with mobile specific performance metrics (startup time, screen render time, network call latency, ANR analysis) in a session level timeline. It's not traditional server side APM, but it covers mobile performance layer that server monitoring tools miss entirely.
For mobile teams, Embrace often replaces both error tracker and mobile performance monitor. It doesn't cover backend infrastructure, so teams with complex server architectures still need a separate APM for backend side.
Raygun: crash + APM in one product
Raygun bundles crash reporting, real user monitoring, and APM in a single product starting at ~$49/month. For teams that want both capabilities without buying separate tools, bundle is cheapest path.
The tradeoff: Raygun's mobile specific depth (ANR grouping, OEM fragmentation handling, breadcrumb detail) is less mature than Sentry's or Embrace's.
When is error tracking alone enough?
For most mobile teams, error tracking alone covers 90% of debugging needs. You don't need APM if:
- Your app is mobile only or mobile first with a simple backend (REST API + database, no microservices)
- Your primary debugging problem is "app crashes" not "app is slow"
- Your team is under 10 engineers and can't justify a second monitoring tool's cost and configuration overhead
- You're using Crashlytics (free) or Sentry Team ($26/seat/month) and crash free rate is your primary quality metric
The decision to add APM is triggered by a specific problem, not by a maturity milestone. If your users aren't reporting slowness and your crash free rate is above 99%, adding APM won't improve outcomes.
SREs on r/sre debating whether APM and observability are same thing converge on a practical answer: if your primary debugging loop is "find crash → read stack trace → fix code → ship," you need error tracking and nothing else. APM enters picture when debugging loop becomes "users say it's slow → crash reports show nothing → you need to trace latency across services."
When do you need APM alongside error tracking?
You need APM when crashes alone don't explain user experience problems you're seeing.
- Users report "app is slow" but your crash reports show nothing. The problem is latency, not failure, and error tracking doesn't measure latency
- Mobile timeouts appear as crashes but are actually slow API responses. Without tracing request through backend, you can't distinguish a real crash from a timeout
- Your backend is microservices based and a mobile error could originate from any of 10+ services. Distributed tracing connects mobile request to backend bottleneck
- You're seeing high ANR rates but blocked thread is waiting on a network call. You need to see whether network call is slow because API is slow, because database is slow, or because a downstream dependency is slow
The cost math: Sentry Team at $26/seat/month covers error tracking with basic performance, while adding Datadog for full APM starts at hundreds/month for a small team. Raygun bundles both at ~$49/month with less depth, and Embrace covers mobile specific performance at contact us pricing after 1M sessions/month.
Cost comparison
A cautionary thread on r/sre reports observability costs exceeding actual infrastructure costs after adding full APM alongside error tracking: teams start with Sentry for crashes ($130/month), add Datadog for backend tracing ($200+), then find combined monitoring bill is larger than their AWS bill. For mobile teams, this is often avoidable by using Sentry's built in performance traces instead of a separate APM.
Decision framework
Answer these three questions to determine what you need.
Question 1: Is your primary debugging problem crashes or slowness?
If crashes: start with error tracking (Crashlytics or Sentry). If slowness: you need performance monitoring, which means either Sentry's built in traces, Embrace's session metrics, or full APM.
Question 2: Is performance problem on mobile device or in backend?
If slow screen is caused by rendering (heavy images, complex layouts, animations): Embrace's session timeline or Sentry's mobile vitals show device side performance. If slow screen is caused by a slow API call: you need backend tracing, which means Datadog, New Relic, or at minimum Sentry's trace propagation to backend.
Question 3: What's your budget?
Under $50/month: Crashlytics (free) + Sentry free tier for performance traces. $50-150/month: Sentry Team (error tracking + basic performance) or Raygun (bundled). $150-500/month: Sentry Team + Embrace (mobile performance) or Sentry Team + backend APM. $500+/month: Datadog or New Relic for full stack.
How does shift left testing reduce need for both?
Every crash Drizz catches in CI never appears in Crashlytics or Sentry. Every performance regression caught by automated testing on real devices (slow screen loads, unresponsive UI, ANRs) is an issue resolved before it generates an APM alert.
Drizz doesn't replace production monitoring, but fewer issues that make it to production, less you need from both your error tracker and your APM. For teams evaluating whether to add APM, reducing production error volume through pre release testing often delays need for a full APM investment by 6-12 months.
Reddit's own engineering team documented how quarantining flaky tests and parallelizing critical path regression suites in CI reduced number of bugs reaching production. The insight that applies here: if your CI pipeline catches both crashes and performance regressions on real devices, volume of issues that reach your production monitoring tools drops, and threshold for needing dedicated APM rises.
FAQ
What's difference between error tracking and APM?
Error tracking captures crashes, exceptions, and ANRs with stack traces and device context, answering "what broke." APM captures latency, throughput, distributed traces, and database query performance, answering "what's slow." Modern tools like Sentry and Datadog increasingly cover both, but with different depth.
Do I need APM for a mobile app?
Most mobile teams under 10 engineers don't need dedicated APM, since error tracking (Crashlytics or Sentry) with basic performance monitoring covers majority of debugging needs. APM becomes necessary when backend latency is causing mobile side problems that crash reports can't explain.
Which tool covers both error tracking and APM?
Sentry covers error tracking with basic performance monitoring (traces, spans), Datadog covers full APM with error tracking added, Embrace covers mobile specific crash reporting and performance in one tool, and Raygun bundles both at ~$49/month. Each has different depth on each side.
Is Sentry's performance monitoring enough to replace APM?
For mobile teams with simple backends, often yes, since Sentry traces outbound API calls and screen render times. For teams with microservices where you need to trace a request through 10+ backend services, Sentry's performance data stops at API boundary and you need a dedicated backend APM.
How much does APM cost compared to error tracking?
Error tracking ranges from $0 (Crashlytics) to $130/month (Sentry Team for 5 seats), while full APM (Datadog, New Relic) starts at $200+/month and bundled option (Raygun at ~$49/month) covers both with less depth.
When should a startup add APM?
When users report slowness that crash reports don't explain, when mobile timeouts are caused by backend latency you can't diagnose with error tracking alone, or when your backend grows to microservices and you need distributed tracing. Don't add APM preemptively; add it when a specific performance problem demands it.
Can pre release testing reduce need for APM?
Performance regressions caught on real devices in CI (slow screen loads, ANRs, unresponsive UI) are resolved before they generate production APM alerts. This delays need for a full APM investment by catching most visible performance problems before users encounter them.
What's best error tracking tool for mobile apps in 2026?
Crashlytics is free default, and Sentry is best paid option with two way Jira sync, ownership routing, and built in performance monitoring. See best mobile error tracking tools comparison for full evaluation.
