Articles & Guides
Useful resources for web developers and system administrators
Performance
content-visibility: Skipping Work the User Cannot See
Browsers lay out and paint pages nobody has scrolled to. One property skips that work — and without its companion, it trades rendering time for a jumping page.
Performance
Speculation Rules: Prerendering Pages Before the Click
Prerendering makes navigation feel instant by loading the page before the click. It also runs that page, and pays for visits that never happen. Both matter.
Performance
Server-Timing: Making Backend Time Visible in the Browser
A client can measure how long the server took but never what it did. Server-Timing carries the breakdown to the browser and opens the largest interval in a load.
Security
MTA-STS and TLS-RPT: The Control That Can Stop Mail
SPF and DMARC change how mail is classified; MTA-STS changes whether it is delivered. Roll it out with TLS-RPT first, and know what enforce mode really costs.
HTTP
HTTP 413 Request Entity Too Large: Which Layer Rejected It
Five components each enforce their own body-size limit, and one of them returns an empty form instead of a 413. Find the narrowest gate before editing configs.
Networking
ERR_TUNNEL_CONNECTION_FAILED: The Proxy Refused Your CONNECT
The tunnel is a CONNECT request to a forward proxy. Read what the proxy answers, and learn the one server-side setting that causes this for corporate users.
SSL/TLS
Your Connection Is Not Private: Which of Six Errors It Is
The warning is identical for six unrelated faults. The code beneath it says whether the cause is your clock, your network, or the site's certificate.
Security
Cloudflare Error 1015: Why Your Own Visitors Are Rate Limited
Error 1015 is a rule you configured, firing. Find which one matched, check what it counts by, and stop it catching customers, mobile users and your monitoring.
SSL/TLS
ERR_CERT_COMMON_NAME_INVALID: Certificate Name Mismatch
Browsers stopped reading the Common Name in 2017 and match the SAN list instead. Print the names your certificate covers and fix the real mismatch in minutes.
Performance
Website Slow Abroad: Why Distance Multiplies Latency
A healthy server and a four-second load abroad are both real. Distance is paid on every round trip, and a first view spends four or five before any HTML lands.