Measure TTFB (Time To First Byte) for any URL. Get verdict, risk score, and optimization recommendations. Improve Core Web Vitals and server performance.
The TTFB Checker on httpstatus.com measures the Time to First Byte for any URL, breaking the metric into its component phases — DNS resolution, TCP connection, TLS negotiation, and server processing time — so you can identify exactly where delays occur. It tests TTFB across multiple consecutive requests to distinguish first-request cold-start latency from warm-cache performance, and compares results against Google's recommended 200ms threshold for good Core Web Vitals scores. The tool also tracks TTFB variation over repeated measurements to detect inconsistent server performance.
DevOps engineers diagnosing slow origin servers behind CDN layers use this tool to separate TLS negotiation overhead from actual server processing time — discovering that 180ms of a 220ms TTFB is TLS handshake time (indicating the CDN is forwarding connections to origin without TLS session reuse) focuses the optimization effort on enabling TLS session resumption rather than application-level changes. Google's Core Web Vitals guidance classifies TTFB above 800ms as poor and notes it directly constrains LCP performance, making sub-200ms TTFB a prerequisite for achieving a 'Good' Core Web Vitals designation.