flate2 1.0.17

DEFLATE compression and decompression exposed as Read/BufRead/Write streams. Supports miniz_oxide, miniz.c, and multiple zlib implementations. Supports zlib, gzip, and raw deflate streams.


Crates.io Documentation

A streaming compression/decompression library DEFLATE-based streams in Rust.

This crate by default uses the miniz_oxide crate, a port of miniz.c to pure Rust. This crate also supports other backends, such as the widely available zlib library or the high-performance zlib-ng library.

Supported formats:

  • deflate
  • zlib
  • gzip
# Cargo.toml
flate2 = "1.0"


use std::io::prelude::*;
use flate2::Compression;
use flate2::write::ZlibEncoder;

fn main() {
    let mut e = ZlibEncoder::new(Vec::new(), Compression::default());
    let compressed_bytes = e.finish();


use std::io::prelude::*;
use flate2::read::GzDecoder;

fn main() {
    let mut d = GzDecoder::new("...".as_bytes());
    let mut s = String::new();
    d.read_to_string(&mut s).unwrap();
    println!("{}", s);


The default miniz_oxide backend has the advantage of being pure Rust, but it has relatively low performance. For higher performance, you can use zlib instead:

flate2 = { version = "1.0", features = ["zlib"], default-features = false }

This supports either the high-performance zlib-ng backend (in zlib-compat mode) or the use of a shared system zlib library. To explicitly opt into the fast zlib-ng backend, use:

flate2 = { version = "1.0", features = ["zlib-ng-compat"], default-features = false }

Note that if any crate in your dependency graph explicitly requests stock zlib, or uses libz-sys directly without default-features = false, you'll get stock zlib rather than zlib-ng. See the libz-sys README for details.

For compatibility with previous versions of flate2, the cloudflare optimized version of zlib is available, via the cloudflare_zlib feature. It's not as fast as zlib-ng, but it's faster than stock zlib. It requires a x86-64 CPU with SSE 4.2 or ARM64 with NEON & CRC. It does not support 32-bit CPUs at all and is incompatible with mingw. For more information check the crate documentation. Note that cloudflare_zlib will cause breakage if any other crate in your crate graph uses another version of zlib/libz.

For compatibility with previous versions of flate2, the C version of miniz.c is still available, using the feature miniz-sys.


This project is licensed under either of

at your option.


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this project by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.