Raw DEFLATE Compress and Decompress

What is raw DEFLATE?

Raw DEFLATE is the compressed bytes themselves, with no header and no checksum. Gzip and zlib both wrap this stream, and a zip entry often stores it directly.

This tool compresses bytes into a raw DEFLATE stream, or decompresses one back to the original bytes.

Raw DEFLATE options

Input

Pasted text up to 100 MiB, read as UTF-8, or a file up to 2 GiB. A file is read in pieces and is not held whole.

Action

Compress (the default) or Decompress. Decompress reads raw DEFLATE only. It does not guess gzip or zlib.

Level

A whole number from 0 to 9. 0 stores the bytes with almost no compression, so the file can come out slightly larger than the input. 9 spends more time for a smaller result. The default is 6, and the level is ignored when you decompress.

Filename

Optional. Compress adds .deflate. Decompress removes one trailing .deflate. Left blank, an upload keeps its own name and pasted text downloads as output.deflate or output.bin.

• The result is a file download. Expanding pasted text stops at 200 MiB and expanding a file at 4 GiB.

Why a DEFLATE stream with no header exists

A container that already records the length and a checksum does not need another one. Zip entries, and the compressed data inside PNG, keep the wrapper outside the DEFLATE bytes so it is not counted twice.

Without that wrapper, the bytes do not identify themselves. This tool trusts the action you pick. It does not inspect the input and decide which format it is.

Raw DEFLATE alternatives

Gzip and zlib are the same compressed bytes with a header and a checksum. This page will not open those. A .br (Brotli) or .zst (Zstandard) file is a different algorithm and will not open here either.

The gzip command can inflate a stream with gzip -d only when the stream is actually gzip. For a raw stream larger than 2 GiB, Python's zlib with a negative window, or openssl zlib, are the usual choice.

Things to know about raw DEFLATE

Phil Katz designed DEFLATE for PKZIP. The format of the raw stream is RFC 1951, and the specification writes the name in capitals. There is no standard file suffix, so this tool uses .deflate to keep the download easy to tell apart from a gzip or zlib file.