File Compressor

About File Compressor

This tool compresses files to reduce their size using GZIP, ZIP, or DEFLATE algorithms. Upload your file, choose compression format and level, and download the compressed result. Useful for reducing file sizes for storage or transfer. All processing happens in your browser for complete privacy.

How does file compression work?

Upload a file, select compression format (GZIP, ZIP, or DEFLATE) and level, then click Compress. The tool will compress your file and show the size reduction. You can then download the compressed file.

What compression formats are available?

GZIP (.gz) - Standard compression for single files, widely supported. ZIP (.zip) - Archive compression, can be extracted by standard tools. DEFLATE (.zz) - Raw deflate compression algorithm.

What are compression levels?

Fast (1) - Quick compression, larger file size. Balanced (6) - Good compromise, recommended for most uses. Maximum (9) - Best compression, slower processing. Higher levels take longer but produce smaller files.

What file types compress well?

Text files, code, logs, and documents compress very well (often 70-90% reduction). Images, videos, and already-compressed files (JPEG, MP4, ZIP) don't compress much further as they're already optimized.

Why is my compressed file larger?

Some files (especially images, videos, or already-compressed files) may become slightly larger due to compression overhead. These files are already optimized and won't benefit from additional compression.

How do I decompress the file later?

GZIP files can be decompressed using gunzip, 7-Zip, WinRAR, or our extraction tools. ZIP files work with any standard archive tool. DEFLATE files need specialized tools.

Is there a file size limit?

There's no strict limit, but very large files (over 1GB) may be slow to process or fail depending on your browser's available memory.

Which compression level should I choose?

For web assets you serve repeatedly (Content-Encoding), use Maximum (9) since it is compressed once and downloaded many times. For one-off transfers or large logs where speed matters, Balanced (6) is usually within a fraction of a percent of level 9. Enable 'Compare compression levels' to see the actual byte savings of 1 vs 6 vs 9 for your file - often level 9 saves under 1% over level 6, so the extra time is rarely worth it.

Is the compression lossless?

Yes. GZIP (RFC 1952), ZLIB/DEFLATE (RFC 1950 / RFC 1951) and ZIP all use the DEFLATE algorithm, which is fully lossless - decompressing returns a byte-for-byte identical copy of your original file. Nothing is discarded, so it is safe for source code, databases, logs and any data where integrity matters. Note that GZIP and DEFLATE here produce a single compressed stream, while ZIP stores your file as an entry inside an archive.

Is my file safe?

Yes! All compression happens directly in your browser using JavaScript. Your file is never uploaded to any server. Everything stays private on your device.