File Compressor
Compress any file online for free using gzip, right in your browser. Reduce file size before sending or storing, no uploads, fully private.
About This Tool
Reduce the size of any file using gzip, the same compression format used by web servers and command-line tools like gzip and tar. Useful for shrinking logs, text exports, or other compressible files before sending or archiving them. Batch compress multiple files at once, all in your browser.
How To Use
- Drop your files into the upload zone or click to select them.
- Click "Compress", no settings to configure.
- Each file is gzip-compressed in your browser.
- Download your compressed .gz files individually or as a ZIP.
How It Works
Compression uses the browser's native CompressionStream API set to gzip mode, the same DEFLATE-based algorithm used by the standard gzip command-line tool and by most web servers for compressing responses. Your file's bytes are streamed through this compressor without ever being fully loaded into a different format first.
How much a file shrinks depends entirely on its content. Plain text, logs, source code, and other repetitive or human-readable formats often compress by 60-90%. Files that are already compressed, such as JPEG images, MP4 videos, or ZIP archives, will barely shrink at all, since there's little redundancy left to remove.
The output is a standard .gz file, openable by gzip, 7-Zip, and most archive managers. Everything runs inside a Web Worker on your device; your files are never uploaded.
Frequently Asked Questions
What file types compress best?
Text-based formats: plain text, CSV, JSON, XML, source code, and logs. These often shrink by 60-90%. Already-compressed formats like JPEG, MP4, or ZIP will barely change size.
How do I open a .gz file?
Most archive managers (7-Zip, The Unarchiver, macOS Archive Utility) open .gz files directly. On Linux and macOS, the `gunzip` or `gzip -d` command also works.
Can I compress multiple files at once?
Yes. Batch processing compresses every file you upload, up to 50 files at once, and bundles the results into a ZIP for convenient downloading.
Is this the same as zipping a file?
Similar idea, different container. This produces a single-file .gz, the format used by the gzip tool, rather than a multi-file .zip archive. Use our Zip Files tool if you want a .zip instead.
Are my files uploaded to a server?
No. Compression happens entirely in your browser using the native CompressionStream API. Your files never leave your device.