Sentry
Sentry is an open-source platform for workflow productivity, aggregating errors from across the stack in real time.
What detecting Sentry tells you about a site
Sentry is the most widely deployed error- and performance-monitoring SDK, and it is easy to spot from the client. The tells are the Sentry bundle loaded from a browser.sentry-cdn.com / js.sentry-cdn.com host (or self-hosted), a Sentry.init({ dsn: ... }) call in the HTML, the sentry-trace and baggage headers on instrumented requests, and error/span payloads sent to a *.ingest.sentry.io endpoint. Detecting it signals a team that instruments production reliability — exception capture, release tracking and often tracing — i.e. a real engineering organisation with an on-call culture.
The detail that matters for Sentry
The presence of sentry-trace/baggage headers (not just error capture) means distributed tracing is enabled, implying the team monitors performance across services end to end, not merely crashes.
Sentry in a real-world stack
When you find Sentry, it rarely travels alone. Spans the whole stack: a browser SDK plus matching server SDKs (Node, Python, etc.), commonly wired into Slack/PagerDuty alerting.
About
Sentry is an open-source platform for workflow productivity, aggregating errors from across the stack in real time.
Categories: Issue trackers
Quick facts
How we detect Sentry
Sourcemap Explorer carries 11 fingerprint signals for Sentry, spread across 4 channels — response header, javascript global, html source and script src url. The exact patterns are listed below, and you can replay each one in Chrome DevTools to confirm a match by hand.
Each signal alone is rarely conclusive — Sourcemap Explorer cross-references all of them and weights by confidence. You can reproduce any of these checks yourself in Chrome DevTools.
Server-side fingerprint: the response header reveals the technology behind the page. Visible in DevTools → Network → response headers.
Sentry-Trace:
Window-level global the technology installs on page. Reproducible by typing the path into the DevTools console.
window.Raven.config
window.SENTRY_SDK_SOURCE
window.Sentry
window.Sentry.SDK_VERSION = (.+)
window.__SENTRY__
window.ravenOptions.whitelistUrls
Substring or regex match against the page HTML — typically a unique class, comment marker, or asset path.
<script[^>]*>\s*Raven\.config\('[^']*', \{\s+release: '([0-9\.]+)'<script[^>]*src="[^"]*browser\.sentry\-cdn\.com/([0-9.]+)/bundle(?:\.tracing)?(?:\.min)?\.js
Script URL pattern. Typically a CDN host or chunk path that ships with the technology.
browser\.sentry\-cdn\.com/([0-9.]+)/bundle(?:\.tracing)?(?:\.min)?\.js
\.sentry-cdn\.com/
FAQ
How do I check if a website is using Sentry?
Open the page in Chrome, click the Sourcemap Explorer toolbar icon, and read the Stack tab. Sentry's specific fingerprints here are response header, javascript global, html source and script src url, and the popup flags Sentry whenever any combination of them is found. The same checks can be reproduced manually in DevTools — see the "How we detect" section above.
What Sentry version can Sourcemap Explorer detect?
Sentry ships as a hosted issue trackers rather than a bundled npm package, so version-specific detection isn't always possible. Where the platform leaks a version in response headers (`X-Powered-By`, `Server`, generator meta tags) we surface it; otherwise we report presence only.
Where can I read more about Sentry?
Official site: https://sentry.io/. For Sourcemap Explorer's detection guide, see the deep-dive link below or the related guides in the cross-link section.
Detected by Sourcemap Explorer
Open the popup on any page running Sentryand you'll see the exact version pulled from the bundled package.json when sourcemaps are exposed.