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HTTP Server-Timing & Resource Timing: Measuring the Real Costs

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Measuring web performance: where does the time actually go?

A page that takes 3 seconds to load — where did those 3 seconds go? DNS? TLS? Server processing? Downloading images? Without measurement, optimization is guesswork. Two browser APIs answer this precisely: Resource Timing (browser-measured network phases for every request) and Server-Timing (server-reported backend processing breakdown).

Together, they give you a complete timeline: DNS resolution, TCP connect, TLS handshake, time-to-first-byte (TTFB), and download duration — for every resource on the page, with server-side detail about what the backend was doing during TTFB.

Packets in motion — click to inspect:

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