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GZIP Compressor

Compress a file to .gz in your browser. Choose level 1, 6 or 9; the output is measured byte for byte, never estimated.

Choose a file

Compressed

The .gz appears here with exact byte counts.

Your file is never sent to a server. It is read and processed by your own browser, and the results are not stored.

How to use it

  1. Choose one file.
  2. Pick level 1, 6 or 9.
  3. Compress; check the before and after sizes; download the .gz.

Limits worth knowing

  • 512 MB input ceiling to protect the tab.
  • Level 9 is proportionally slower on large files; use level 6 if you are iterating.
  • gzip does not store the file name or timestamps — decompressing gives the same bytes back, without metadata.
  • Already-compressed files (JPEG, ZIP, MP4) gain nothing; the tool says when output is larger than input.

Why gzip is still everywhere

gzip compresses streams with DEFLATE and stores them with a tiny header: magic bytes, flags, CRC-32 and the uncompressed size. That is metadata, not recovery tooling — there is nothing to "fix" in a .gz, which is why every Unix has had gunzip for thirty years.

For text-based formats, the difference between levels 6 and 9 is real but modest; for already-compressed data it is noise. Measure before/after — the tool shows the real numbers.

What gzip does not do

No names, no directories, no permissions. If you need those, make a tar of the folder first, then compress — or use create-zip-archive-online, which stores structure metadata.

Frequently asked questions

Does GZIP Compressor upload my files to any server?

No. GZIP Compressor runs in your browser, and the file is read there rather than sent to a server for processing. Our host still sees ordinary page-request metadata, which is described on the privacy page.

Is GZIP Compressor free to use?

Yes, GZIP Compressor is free, with no paid tier, no account, and no watermark added to your output. The limits are technical rather than commercial: file size, page count and supported formats are listed on this page.

What file formats and sizes are supported?

GZIP Compressor supports * files up to 512MB directly in your browser.

Which level should I pick?

Level 1 is fastest and compresses least. Level 6 is a good default. Level 9 takes longer and gives the smallest file for compressible text — logs, CSS, JSON, code.

Is the reported size real?

Yes. The tool compresses first and then measures the actual bytes with TextEncoder — no estimate from compressibility heuristics.

Can I decompress it elsewhere?

gzip is the same format everywhere: gunzip on the command line, tar -xvzf, every archive tool reads .gz.

Is my file uploaded?

No. Compression runs in this tab; the .gz is assembled in memory and offered as a download.