What files benefit most from gzip?

Text-based data: JSON, CSV, HTML, CSS, JavaScript, logs. These often shrink by 70–90%. Media files that are already compressed see little or no benefit, which the tool reports honestly.

Is gzip compression lossless?

Yes — completely. Decompressing a .gz produced here returns byte-for-byte the original file.

Does my file leave my computer?

No. Compression and decompression run in your browser via built-in APIs. There is no upload endpoint and no server-side processing.

Gzip or ZIP — which should I use?

For a single file, gzip is the leaner choice and is universally understood by servers and pipelines. For bundling multiple files into one archive, use ZIP. Both are available as separate tools.

Compress to GZIP — in your browser

Turn any file into a .gz archive — or open a .gz to recover the original — using the Compression Streams API built into your browser. No upload, no install, no account.

Open the GZIP compressor tool Runs entirely in your browser — files never leave your device.

What this tool does

GZIP is the universal compression format of the web: text assets, logs, CSVs and JSON routinely shrink dramatically with it. This tool uses the native Compression Streams API where available (with a compatible fallback), so compression is fast and happens entirely on your device.

Extraction works the same way: the .gz file is decompressed in your browser and the original bytes are offered as a download. Nothing is transmitted in either direction.

How to gzip a file without uploading it

Add the file. Drop any file — or an existing .gz — into the home-page tool.
Compress or extract. Choose GZIP compression to produce a .gz, or extraction to get the original back.
Save it. The result downloads locally, with the measured size change shown honestly.

Supported operations

This list is generated from CompressKit's capability registry — only implemented and tested operations appear here.

Reduce file size

Produce a .gz using the browser Compression Streams API (fflate fallback where the API is missing).
Extract content

Decompress a .gz file and download the original content.

Frequently asked questions

What files benefit most from gzip?: Text-based data: JSON, CSV, HTML, CSS, JavaScript, logs. These often shrink by 70–90%. Media files that are already compressed see little or no benefit, which the tool reports honestly.
Is gzip compression lossless?: Yes — completely. Decompressing a .gz produced here returns byte-for-byte the original file.
Does my file leave my computer?: No. Compression and decompression run in your browser via built-in APIs. There is no upload endpoint and no server-side processing.
Gzip or ZIP — which should I use?: For a single file, gzip is the leaner choice and is universally understood by servers and pipelines. For bundling multiple files into one archive, use ZIP. Both are available as separate tools.

Ready to try it?

The GZIP compressor tool runs on this site with no upload step — your file is processed by your own browser and saved back to your device.

Open the GZIP compressor tool