Gzip Decompressor & Compressor

When compressing already-small or highly random data, Gzip compression may not reduce size, and Base64 encoding adds ~33% overhead. This tool shows the size comparison so you can evaluate the benefit.

This tool processes data entirely in your browser. Very large inputs (several MB) may work but could slow down your browser. For production compression of large files, use server-side tools.

No. Gzip compresses a single stream or file. The .zip format is an archive format that can contain multiple files with individual compression. Gzip is simpler and often used for single-file compression and HTTP content encoding.

Paste the Base64 string into the input box with Decompress mode selected. The tool first decodes Base64 back to binary gzip bytes, then decompresses them with the DEFLATE algorithm and shows the readable text. No manual two-step decoding is needed.

All three use the same DEFLATE compression algorithm but wrap it differently. Zlib adds a small header and checksum around the raw deflate stream. Gzip wraps deflate in a file format with a header, timestamp, and CRC32 checksum. In HTTP Content-Encoding, "gzip" is the standard value even though the payload is usually just a gzip-wrapped deflate stream.

gzip file.txt compresses to file.txt.gz and deletes the original; -k keeps it. Decompress with gunzip file.txt.gz or gzip -d. For many files at once, tar czf archive.tar.gz dir/ bundles and compresses in one step, and tar xf unpacks. zcat streams a .gz file without writing anything - handy for compressed logs.

This page does not offer a compression-level selector. It uses the encoder’s default settings; the result depends on your input. If you need a specific level, use a compression tool that exposes that setting.

zlib exposes levels 1-9: 1 is fastest with the largest output, 9 squeezes hardest and slowest, and 6 is the default near the sweet spot for text. Levels 7-9 usually win only single-digit percentages over 6 while taking noticeably longer. For web responses, CPU time often matters more than the last 5% of size.