.svgz File Extension

What kind of file is a .svgz?

An .svgz file is Scalable Vector Graphics compressed with Gzip. After decompression, its content is the same XML-based vector artwork normally stored in an .svg file. W3C recommends the lowercase .svgz suffix for this convention.¹

SVGZ commonly uses the image/svg+xml MIME type together with a gzip content encoding. It is not a separate graphics language, and application/gzip alone says only that the outer stream is compressed.

The outer file begins with Gzip magic bytes 1F 8B. A reliable check must then decompress the stream, parse the result as XML, and confirm an svg root element in the http://www.w3.org/2000/svg namespace. The Gzip signature by itself does not prove that the payload is SVG.²

How do I open a .svgz on my computer?

• On Windows or macOS, Adobe Illustrator can open and save SVG Compressed files.³
• On Windows, macOS, or Linux, Inkscape supports compressed Inkscape SVG and compressed plain SVG.⁴
• On any system with Gzip tools, decompress the file before viewing or editing its XML.

For example, write an ordinary SVG copy without changing the original:

gzip -dc drawing.svgz > drawing.svg

Then open drawing.svg in a current browser, vector editor, or text editor. A browser may display SVGZ delivered by a web server, but the server must send image/svg+xml and the correct Content-Encoding: gzip header. Incorrect headers are a common reason an otherwise valid file downloads or fails to render.⁵

Poly support for .svgz

Poly safely stores, syncs, shares, versions, and downloads .svgz files, and makes them searchable by filename. It does not currently infer or decompress SVGZ for image processing, so it does not generate an SVG thumbnail, visual search representation, in-app image preview, or agent-readable rendering from this suffix.

Decompress the file to .svg before adding it to Poly when you need those image features. Keep the .svgz original too if it is part of a web deployment or design handoff.

History of .svgz

W3C published SVG 1.0 as a Recommendation on September 4, 2001. That first specification recommended .svg for ordinary SVG and .svgz for its Gzip-compressed form.¹⁶ The convention was useful because verbose XML often compresses well while retaining the SVG drawing after decompression.

W3C later reported five sample SVG documents shrinking by 77% to 84% with Gzip. Those figures illustrate the potential rather than guarantee a result. Files dominated by already compressed JPEG or PNG images usually save less.⁷

Working with .svgz and alternatives

For modern websites, an uncompressed .svg resource with server-managed HTTP compression is often simpler. The filename and media type remain ordinary SVG, while the server negotiates compression for transfer.⁵

Treat untrusted SVGZ as both compressed input and potentially active SVG. Limit decompression resources, then inspect scripts, event attributes, links, external resources, and foreignObject content before publishing or opening it in a document context.⁸