LiteJS Zip –

Lightweight (~1.3KB) ZIP file creator for Browser and Node.js. No dependencies.
Uses the CompressionStream API if available; otherwise uses provided deflater or creates an uncompressed ZIP.

createZip(files [, options] [, callback])

• files: Array of {name, content[, time]}
• options: { deflate: deflateRawSync, comment: 'Comment for a file' } (optional custom deflater makes ZIP creation synchronous)
• callback: Optional (err, zip) callback

Returns a Promise<Uint8Array>, or invokes provided callback, or the ZIP synchronously when using a custom deflater.

Examples

const { createZip } = require("@litejs/zip")

// Async usage
const zipUint8Array = await createZip([
    { name: "file-a.txt", content: "Some content" },
    { name: "dir/file-b.txt", content: Uint8Array.from("012"), time: new Date(2020, 1, 21) },
])

// Callback style
createZip(files, { comment: "Some comment for a zip file" }, (err, zipUint8Array) => {
    // Handle ZIP file content
})

// With custom deflate runs synchronously
const zlib = require("zlib")
const zipInSync = createZip(files, { deflate: zlib.deflateRawSync })

Unzip

unzip(src [, options])

• src: Uint8Array, ArrayBuffer or read function
• options: lsZip and catZip options

Reads all entries to memory, use lsZip and catZip for individual files.

lsZip(src [, options]) and catZip(src, entry [, options])

• src: zip bytes or read function
• read: (start, end) => bytes with Uint8Array.subarray semantics, negative start counts from the end. Returns the requested bytes or the whole file as Uint8Array or ArrayBuffer, or a Promise of one.
• options: { tail: 65557 } for lsZip, bytes read from the end to find the central directory. { inflate: (data, entry) => bytes } for catZip, otherwise DecompressionStream is used. Limit the output to entry.size against zip bombs, DecompressionStream is limited already.

Zip64 is read when 32-bit fields hold real values (under 4 GB / 65534 entries).

const { lsZip, catZip, unzip } = require("@litejs/zip/unzip.js")

// Blob or File in browser
const read = (start, end) => file.slice(start, end).arrayBuffer()

// HTTP Range request, read single file from zip on remote server
// Cross-origin need Range in Access-Control-Allow-Headers.
const read = (start, end) => fetch(url, {
    headers: { Range: "bytes=" + (start < 0 ? start : start + "-" + (end - 1)) }
}).then(res => res.arrayBuffer())

// File system
const fd = fs.openSync("file.zip"), size = fs.fstatSync(fd).size
const read = (start, end = size) => {
    if (start < 0) start = Math.max(0, size + start)
    const buf = new Uint8Array(end - start)
    fs.readSync(fd, buf, { position: start })
    return buf
}

const list = await lsZip(read)
const firstFile = await catZip(read, list[0])

// Whole zip at once, edit and zip again
const files = await unzip(zipUint8Array, {
    inflate: (data, entry) => zlib.inflateRawSync(data, { maxOutputLength: entry.size })
})
const newZip = await createZip(files.filter(file => !file.name.endsWith(".log")))

Contributing

Follow Coding Style Guide, run tests npm install; npm test.

Copyright (c) 2023-2026 Lauri Rooden <lauri@rooden.ee>
MIT License | GitHub repo | npm package | Buy Me A Tea