Header Watch: Security Monitor

Header Watch keeps a silent eye on the security headers of any website you care about. Drop in a URL, let it scan, and you get a baseline snapshot. From then on, it checks automatically in the background and notifies you the moment anything changes.

Security headers like Content Security Policy, HSTS, X-Frame-Options, and Permissions-Policy are easy to misconfigure during a deployment, a server migration, or a routine update — and just as easy to miss. Header Watch catches the drift so you don't have to.

Add any URL you want to watch. Header Watch fetches the headers, grades them, and stores a baseline. Background checks run every 1, 6, or 24 hours depending on what you set. When something changes you get a push notification with a summary of exactly what was added, removed, or altered.

The drift event log keeps a full history of every change, so you can see precisely when a header was removed or a value was modified. Each watch shows a side-by-side comparison between the baseline and the current state.

Built for developers monitoring their own sites, security engineers keeping tabs on third-party services, or anyone who wants to know the moment a Content Security Policy quietly disappears after a CDN update.

No account required. Everything runs on device.