Always-on monitoring of Time to First Byte. TTFB is one of the four sub-parts of LCP - the front-end cannot recover an LCP budget the server has already burned through. Sentry catches origin slowdowns, missing compression, and CDN gaps. Cortex handles the fix.
Continuous audits of mobile + desktop TTFB against Google's 800ms threshold and the documented infrastructure checks that explain why the server is slow. Each rule maps to a primary web.dev or Google Search Central doc. Sentry catches what fails. Cortex fixes it.
CrUX 28-day p75 TTFB on phone form factor under Google's 800ms 'Good' threshold. TTFB itself isn't a direct ranking signal, but it's the largest input into LCP and FCP - which are. Field TTFB is what real users on real networks actually experience.
CrUX 28-day p75 TTFB on desktop under Google's 800ms 'Good' threshold. Desktop field TTFB matters for office/cable users who otherwise enjoy fast connections.
Lighthouse server-response-time audit reports the origin response time under 800ms on the throttled mobile run. Lab TTFB is deterministic - surfaces regressions before field data updates.
Lighthouse uses-http2 audit passes - the origin serves resources over HTTP/2 or HTTP/3, not HTTP/1.1. Multiplexed connections + header compression cut TTFB on every request after the first.
Lighthouse uses-text-compression audit passes - HTML, CSS, and JS are served with gzip or Brotli encoding. Brotli typically reduces transfer size 20-30% beyond gzip; both shave 100-300ms off TTFB on slow networks.
`<link rel='preconnect'>` declarations for the cross-origin hosts that serve render-blocking resources (CDN, font host, analytics). Saves the DNS + TCP + TLS round-trips that bloat TTFB on cold connections.
Response headers indicate a CDN edge (Cloudflare cf-ray, Fastly x-served-by, Vercel x-vercel-cache, Akamai x-akamai-edge, AWS x-amz-cf-id). CDN edges serve cached HTML at sub-100ms TTFB regardless of origin location.
Lighthouse server-response-time under 400ms. Half the official 'Good' threshold leaves room for the four other LCP sub-parts (resource load delay, resource load duration, element render delay) to stay within the 2.5s LCP budget.
Paste your homepage URL. Sentry runs PSI for mobile + desktop, pulls 28-day CrUX field TTFB, inspects Lighthouse's HTTP/2, text-compression, preconnect, and server-response-time audits, and probes response headers for a CDN. No signup, instant results, always free.
Sentry fetches your site, runs every TTFB rule, and renders the full result page before your next sip of coffee.
Each failed rule ships with a prescription paragraph. Hand it to engineering and the gap is closed before lunch.
Add your site to the daily Sentry sweep with one click. New regressions get caught the next morning.
8 rules in the TTFB Sentry. Daily 3:30 AM ET sweep.
One brain. Thirty-six pairs of eyes. Sentries monitor every visibility signal that decides whether search engines, AI engines, and ad platforms show you. Cortex reads what they see, weighs it against a unified corpus of platform documentation, and acts. Every move follows a defined decision protocol: action stated, reason given, impact named.