What is Error Monitoring?
Automatically catching and reporting errors when your app breaks.
In plain English
Error monitoring means your app automatically captures errors (crashes, exceptions, bugs) and sends them to a dashboard where you can see them. Without error monitoring, you only find out about bugs when a user complains. With error monitoring, you know about bugs before users do — and you can fix them before they affect more people. Sentry is the most famous error monitoring tool. FlareLog is like Sentry but built for Cloudflare Workers and vibe coders.
Why it matters
Users don't email you when your app breaks. They just leave. Error monitoring catches crashes automatically, so you know about them instantly — not next week when your churn rate spikes. For vibe-coded apps, this is especially important because you didn't write the code yourself, so you can't intuitively know where bugs might be.
How FlareLog handles it
FlareLog captures errors in three ways: (1) the SDK catches exceptions thrown during request handling, (2) the Tail Worker catches crashes that happen before your code runs (CPU timeout, OOM, startup failure), and (3) auto-capture hooks console.error and unhandled promise rejections. No other tool catches all three on Cloudflare Workers.
FAQ
What's the difference between FlareLog and Sentry?
Sentry is great for client-side errors (React, React Native) and has hundreds of integrations. But on Cloudflare Workers, Sentry can't see crashes that happen before your code runs. FlareLog's Tail Worker can. Many teams run both — Sentry for the frontend, FlareLog for the Workers layer. See our Sentry comparison for the full breakdown.
Do I need to add error handling to my code for FlareLog to work?
No. The SDK auto-captures uncaught errors and unhandled promise rejections. Even if your code has zero try/catch blocks, FlareLog will still catch crashes. But adding try/catch with logger.logError() gives you better context (custom metadata, breadcrumbs) for debugging.