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Web app monitoring

Your Web App Returns 200 OK. But Does It Actually Work?

Web apps are built on layers of JS bundles, API calls, third-party scripts, and dynamic rendering. A health check endpoint returning 200 tells you the server is running — not that the React app hydrates, the checkout flow renders, or the auth script loads. Sitewatch monitors the output layer that users actually see, catching deploy regressions and asset failures that infrastructure monitoring misses.

  • Deploy hooks trigger instant checks after every ship
  • Validates JS bundles, CSS, images, and third-party scripts
  • API endpoint monitoring for health checks and critical endpoints
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Common web app failures

The failures your health check endpoint won't catch

Broken JS bundle after deploy

Critical

Your deploy changes the bundle hash. The CDN purges the old file. Your health check returns 200 because the server is fine. But the React/Vue/Svelte app that makes your product work never loads.

Hydration failure

Critical

Server-side rendering works, but the client JS fails to hydrate. The page looks correct on first paint but every interactive element — forms, buttons, modals — is dead. No errors in your monitoring.

Auth provider script failure

Critical

Your OAuth provider's JS SDK fails to load from their CDN. Your login page renders but "Sign in with Google" does nothing. Your infrastructure is healthy. The dependency isn't.

Regional CDN failure

Moderate

Your CDN edge in a specific region serves an old or corrupted asset. Users in the US see a working app. Users in Europe see a broken one. Your single-region health check shows green.

CSS framework mismatch

Moderate

A deploy ships new HTML that references Tailwind classes not in the compiled CSS. Components render with missing styles, broken layouts, invisible text.

API endpoint regression

Critical

A backend deploy changes an API response format. The frontend JS crashes parsing the unexpected shape. The API returns 200, the frontend throws silently.

11

Detection rules

5–30 min

Check intervals

23+

Stack playbooks

Built for web app teams

Monitor what your users actually experience

Post-deploy verification

Connect your Vercel, Netlify, or GitHub Actions pipeline. Every deploy triggers an instant check of your app's critical pages and every linked asset.

API endpoint monitoring

Monitor your health check endpoints, public APIs, and critical backend routes. Check status codes, response times, and content validation.

Stack-aware diagnosis

Running Next.js? Nuxt? Remix? SvelteKit? Sitewatch detects your framework and provides fix playbooks specific to your stack — not generic troubleshooting.

Multi-region checks

Validate your app works from both EU and US regions. Catch CDN edge failures and regional routing issues before users report them.

Fits your existing workflow

From deploy to verified

01

Ship your deploy

Merge to main, push to production, or trigger a release. Your CI/CD pipeline sends a deploy hook to Sitewatch.

02

Every asset is validated

Sitewatch fetches your app's pages, parses the HTML, and validates every linked JS bundle, stylesheet, image, and third-party script.

03

Broken? You'll know immediately

If an asset fails — 404, MIME mismatch, timeout — you get a Slack or email alert with the exact broken resource, root cause, and stack-specific fix steps.

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Web app monitoring FAQ

Know your web app works — not just that the server responds

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