Zlib Compress
Compress any text with the zlib format (RFC 1950) and get the result as Base64 or Hex.
Compress text with zlib (RFC 1950). Free, offline, runs entirely in your browser. Read more Show less
What is zlib?
zlib (RFC 1950) is a lightweight wrapper around raw DEFLATE with a 2-byte header and an Adler-32 trailer. It is the format used by PNG images, HTTP Content-Encoding: deflate, and many programming language APIs (Python's zlib module, Node's zlib module).
How to use
Type or paste text. The tool compresses with zlib and shows the result in Base64 (default) or Hex. zlib data always starts with a byte whose value is one of 0x78, 0x58, 0x48, etc.
FAQ
zlib vs GZIP vs DEFLATE
zlib is DEFLATE with a lighter header. GZIP is DEFLATE with a heavier header, a CRC-32 trailer, and a magic number. Use zlib when a library expects it (PNG, most language stdlibs), GZIP when you need a self-describing format, DEFLATE when you control both ends.
Is my text sent anywhere?
No.
How do I decompress?
Coming in the next wave. For now, use Python's zlib.decompress or Node's zlib.inflateSync.