WEBVTT

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Can a website send the same content in fewer bytes?

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HTTP compression can shrink suitable responses during transfer.

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Understand compressed delivery.
6 useful checks.

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Start with suitable content
HTML, CSS and JavaScript are common candidates for compression.
HTML response · CSS stylesheet · JavaScript file

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The browser advertises support
A request can tell the server which encodings it understands.
Browser capability · Supported encodings · Request headers

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The server sends compressed data
The browser decodes the response before using the content.
Smaller transfer · Content encoding · Decoded content

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Know the common names
Gzip and Brotli are compression methods used on the web.
Gzip · Brotli · Suitable server setup

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Already compressed files differ
Compressing a photo or video again may offer little benefit.
Image encoding · Video encoding · Measure the saving

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Verify actual delivery
Ask your developer to inspect transferred size and response headers.
Correct encoding · Transferred bytes · Working page

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Your checklist
Start with suitable content · The browser advertises support · The server sends compressed data · Know the common names · Already compressed files differ · Verify actual delivery

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Check that compression helps the actual response.
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