Simplest way to download and unzip files in Node.js cross-platform?

Checkout adm-zip

https://github.com/cthackers/adm-zip

ADM-ZIP is a pure JavaScript implementation for zip data compression for NodeJS.

The library allows you to:

decompress zip files directly to disk or in memory buffers compress files and store them to disk in .zip format or in compressed buffers update content of/add new/delete files from an existing .zip

Node has builtin support for gzip and deflate via the zlib module:

var zlib = require('zlib');

zlib.gunzip(gzipBuffer, function(err, result) {
    if(err) return console.error(err);

    console.log(result);
});

Edit: You can even pipe the data directly through e.g. Gunzip (using request):

var request = require('request'),
    zlib = require('zlib'),
    fs = require('fs'),
    out = fs.createWriteStream('out');

// Fetch http://example.com/foo.gz, gunzip it and store the results in 'out'
request('http://example.com/foo.gz').pipe(zlib.createGunzip()).pipe(out);

For tar archives, there is Isaacs' tar module, which is used by npm.

Edit 2: Updated answer as zlib doesn't support the zip format. This will only work for gzip.

yauzl is a robust library for unzipping. Design principles:

• Follow the spec. Don't scan for local file headers. Read the central directory for file metadata.
• Don't block the JavaScript thread. Use and provide async APIs.
• Keep memory usage under control. Don't attempt to buffer entire files in RAM at once.
• Never crash (if used properly). Don't let malformed zip files bring down client applications who are trying to catch errors.
• Catch unsafe filenames entries. A zip file entry throws an error if its file name starts with "/" or /[A-Za-z]:// or if it contains ".." path segments or "\" (per the spec).

Currently has 97% test coverage.

Another working example:

var zlib = require('zlib');
var tar = require('tar');
var ftp = require('ftp');

var files = [];

var conn = new ftp();
conn.on('connect', function(e) 
{
    conn.auth(function(e) 
    {
        if (e)
        {
            throw e;
        }
        conn.get('/tz/tzdata-latest.tar.gz', function(e, stream) 
        {
            stream.on('success', function() 
            {
                conn.end();

                console.log("Processing files ...");

                for (var name in files)
                {
                    var file = files[name];

                    console.log("filename: " + name);
                    console.log(file);
                }
                console.log("OK")
            });
            stream.on('error', function(e) 
            {
                console.log('ERROR during get(): ' + e);
                conn.end();
            });

            console.log("Reading ...");

            stream
            .pipe(zlib.createGunzip())
            .pipe(tar.Parse())
            .on("entry", function (e) 
            {    
                var filename = e.props["path"];
                console.log("filename:" + filename);
                if( files[filename] == null )
                {
                    files[filename] = "";
                }
                e.on("data", function (c) 
                {
                    files[filename] += c.toString();
                })    
            });
        });
    });
})
.connect(21, "ftp.iana.org");

var readPath ="read file location";
var writePath="Write file location ";
fs.createReadStream(reNameReadPath).pipe(unzip.Extract({ path: writePath }));

please see the following link

http://nodejs.org/api/fs.html#fs_fs_renamesync_oldpath_newpath

11/2014: Unfortunately the situation is that there is no good solution to unzipping files in nodejs. There are few libraries each with number of major issues open and contribution stopped long time ago.