How it works
Logs are timestamped lines an app writes as it works (request received, payment failed), best written as structured JSON so they can be searched. Error tracking tools such as Sentry go further: an SDK in the app catches every crash with its stack trace, the browser or device, the release and the steps that led up to it, groups identical errors into one issue and alerts the team. Uploading source maps turns minified browser code back into readable lines.
Metrics (response times, error rates, memory) and traces (one request followed across services) complete the picture; together these are often called observability, and OpenTelemetry is the open standard for collecting them. Common tools include Sentry, Datadog, New Relic, Grafana, Better Stack and Axiom, and Firebase Crashlytics is widely used for mobile crashes. Uptime monitors check a site from outside and alert when it stops answering.
Logging and error tracking pros and cons
Pros
- Find and fix bugs that users never report
- See exactly which release, device and step caused a crash
- Alerts reach the team in minutes instead of days
- Performance data shows which pages and queries are slow
Cons
- Costs grow with traffic and the volume of events sent
- Noisy alerts get ignored unless they are tuned
- Logs can capture personal data or secrets unless they are scrubbed
When to use Logging and error tracking
Pick it when
- Anything real users depend on, from launch day
- Mobile apps, where crashes happen on devices you never see
- Serverless apps, where there is no server to log into
Skip it when
- A short-lived prototype with a handful of friendly testers
Logging and error tracking pricing
Free tier
Sentry has a free Developer plan for one user; Team from about $26 a month (billed yearly, 50,000 errors included) and Business from about $80 a month.
Logging and error tracking pricing page (opens in a new tab)Approximate, checked September 2026.What the other tools cost