Replacements for pako

pako is a JavaScript port of zlib. Its install size is about 2.5 MB, and most of what it does is now available as a smaller package or built into the runtime.

fflate

fflate is a much smaller and faster pure JavaScript implementation with synchronous functions close to pako's.

Be careful with the names: pako.deflate produces the zlib format, which is zlibSync in fflate. fflate's deflateSync is raw deflate, the same as pako.deflateRaw.

pako	fflate
deflate / inflate	zlibSync / unzlibSync
deflateRaw / inflateRaw	deflateSync / inflateSync
gzip / ungzip	gzipSync / gunzipSync

pako.inflate also accepts gzip input. If you relied on that, use decompressSync, which detects zlib, gzip and raw deflate.

import * as pako from 'pako'
import { zlibSync, unzlibSync } from 'fflate'

const compressed = pako.deflate(data) 
const compressed = zlibSync(data) 

const restored = pako.inflate(compressed) 
const restored = unzlibSync(compressed) 

pako 2's { to: 'string' } option has no counterpart (it was also removed in pako 3). Decode the bytes with strFromU8 from fflate or with TextDecoder.

node:zlib (native, Node.js built-in)

Node ships zlib as node:zlib, with the same formats under the same names: deflateSync / inflateSync for zlib, deflateRawSync / inflateRawSync for raw deflate and gzipSync / gunzipSync for gzip. Asynchronous and streaming versions are also available.

import * as pako from 'pako'
import { deflateSync, inflateSync } from 'node:zlib'

const compressed = pako.deflate(data) 
const compressed = deflateSync(data) 

const restored = pako.inflate(compressed) 
const restored = inflateSync(compressed) 

Compression Streams API (native)

CompressionStream and DecompressionStream are available in all modern browsers and as globals in Node 18 and later. The 'deflate', 'deflate-raw' and 'gzip' formats match pako.deflate, pako.deflateRaw and pako.gzip. The API is stream-based and asynchronous, so it fits best where you already work with streams or await.

import * as pako from 'pako'

const compressed = pako.gzip(data) 
const compressed = new Uint8Array( 
  await new Response( 
    new Blob([data]).stream().pipeThrough(new CompressionStream('gzip')) 
  ).arrayBuffer() 
)