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JavaScript obfuscator

logo

JavaScript Obfuscator is a powerful free obfuscator for JavaScript, containing a variety of features which provide protection for your source code.

Key features:

  • variables renaming
  • strings extraction and encryption
  • dead code injection
  • control flow flattening
  • various code transformations
  • and more...

The example of obfuscated code: github.com

Online version:

obfuscator.io

Plugins:

npm version FOSSA Status Build Status Coverage Status Backers on Open Collective Sponsors on Open Collective xscode

You can support this project by donating:

Huge thanks to all supporters!

NOTE! the README on the master branch might not match that of the latest stable release!

If you have a question, check this section first: FAQ

⚠️ Important

Only obfuscate the code that belongs to you.

It is not recommended to obfuscate vendor scripts and polyfills, since the obfuscated code is 15-80% slower (depends on options) and the files are significantly larger.

Installation

Using Yarn or NPM

Install the package with Yarn or NPM and add it to your dependencies or devDependencies:

$ yarn add --dev javascript-obfuscator

or

$ npm install --save-dev javascript-obfuscator

In a Browser

From CDN:

<script src="https://cdn.jsdelivr.net/npm/javascript-obfuscator/dist/index.browser.js"></script>

From node_modules:

<script src="./node_modules/javascript-obfuscator/dist/index.browser.js"></script>

Usage

var JavaScriptObfuscator = require('javascript-obfuscator');

var obfuscationResult = JavaScriptObfuscator.obfuscate(
    `
        (function(){
            var variable1 = '5' - 3;
            var variable2 = '5' + 3;
            var variable3 = '5' + - '2';
            var variable4 = ['10','10','10','10','10'].map(parseInt);
            var variable5 = 'foo ' + 1 + 1;
            console.log(variable1);
            console.log(variable2);
            console.log(variable3);
            console.log(variable4);
            console.log(variable5);
        })();
    `,
    {
        compact: false,
        controlFlowFlattening: true,
        controlFlowFlatteningThreshold: 1,
        numbersToExpressions: true,
        simplify: true,
        stringArrayShuffle: true,
        splitStrings: true,
        stringArrayThreshold: 1
    }
);

console.log(obfuscationResult.getObfuscatedCode());
/*
var _0x9947 = [
    'map',
    'log',
    'foo\x20',
    'bvmqO',
    '133039ViRMWR',
    'xPfLC',
    'ytpdx',
    '1243717qSZCyh',
    '2|7|4|6|9|',
    '1ErtbCr',
    '1608314VKvthn',
    '1ZRaFKN',
    'XBoAA',
    '423266kQOYHV',
    '3|0|5|8|1',
    '235064xPNdKe',
    '13RUDZfG',
    '157gNPQGm',
    '1639212MvnHZL',
    'rDjOa',
    'iBHph',
    '9926iRHoRl',
    'split'
];
function _0x33e4(_0x1809b5, _0x37ef6e) {
    return _0x33e4 = function (_0x338a69, _0x39ad79) {
        _0x338a69 = _0x338a69 - (0x1939 + -0xf * 0x1f3 + 0x1 * 0x469);
        var _0x2b223a = _0x9947[_0x338a69];
        return _0x2b223a;
    }, _0x33e4(_0x1809b5, _0x37ef6e);
}
(function (_0x431d87, _0x156c7f) {
    var _0x10cf6e = _0x33e4;
    while (!![]) {
        try {
            var _0x330ad1 = -parseInt(_0x10cf6e(0x6c)) * -parseInt(_0x10cf6e(0x6d)) + -parseInt(_0x10cf6e(0x74)) * -parseInt(_0x10cf6e(0x78)) + parseInt(_0x10cf6e(0x6a)) + -parseInt(_0x10cf6e(0x70)) + parseInt(_0x10cf6e(0x6e)) * -parseInt(_0x10cf6e(0x75)) + parseInt(_0x10cf6e(0x72)) + -parseInt(_0x10cf6e(0x67)) * parseInt(_0x10cf6e(0x73));
            if (_0x330ad1 === _0x156c7f)
                break;
            else
                _0x431d87['push'](_0x431d87['shift']());
        } catch (_0x9f878) {
            _0x431d87['push'](_0x431d87['shift']());
        }
    }
}(_0x9947, -0xb6270 + 0x4dfd2 * 0x2 + 0x75460 * 0x2), function () {
    var _0x1f346d = _0x33e4, _0x860db8 = {
            'ytpdx': _0x1f346d(0x6b) + _0x1f346d(0x71),
            'bvmqO': function (_0x560787, _0x519b9e) {
                return _0x560787 - _0x519b9e;
            },
            'rDjOa': function (_0x4501fe, _0x2b07a3) {
                return _0x4501fe + _0x2b07a3;
            },
            'xPfLC': function (_0x5f3c9b, _0x434936) {
                return _0x5f3c9b + _0x434936;
            },
            'XBoAA': function (_0x535b8a, _0x42eef4) {
                return _0x535b8a + _0x42eef4;
            },
            'iBHph': _0x1f346d(0x65)
        }, _0x346c55 = _0x860db8[_0x1f346d(0x69)][_0x1f346d(0x79)]('|'), _0x3bf817 = 0x4bb * 0x1 + 0x801 + -0xcbc;
    while (!![]) {
        switch (_0x346c55[_0x3bf817++]) {
        case '0':
            console[_0x1f346d(0x7b)](_0x4c96d8);
            continue;
        case '1':
            console[_0x1f346d(0x7b)](_0x101028);
            continue;
        case '2':
            var _0x65977d = _0x860db8[_0x1f346d(0x66)]('5', -0x586 + -0x2195 + -0x6 * -0x685);
            continue;
        case '3':
            console[_0x1f346d(0x7b)](_0x65977d);
            continue;
        case '4':
            var _0x56d39b = _0x860db8[_0x1f346d(0x76)]('5', -'2');
            continue;
        case '5':
            console[_0x1f346d(0x7b)](_0x56d39b);
            continue;
        case '6':
            var _0x544285 = [
                '10',
                '10',
                '10',
                '10',
                '10'
            ][_0x1f346d(0x7a)](parseInt);
            continue;
        case '7':
            var _0x4c96d8 = _0x860db8[_0x1f346d(0x68)]('5', 0x622 * -0x6 + 0x4a * 0x3 + 0x1 * 0x23f1);
            continue;
        case '8':
            console[_0x1f346d(0x7b)](_0x544285);
            continue;
        case '9':
            var _0x101028 = _0x860db8[_0x1f346d(0x6f)](_0x860db8[_0x1f346d(0x6f)](_0x860db8[_0x1f346d(0x77)], 0x6fb * 0x5 + 0x1ebf * 0x1 + -0x41a5), 0x209 * 0xa + 0x1314 + -0x276d);
            continue;
        }
        break;
    }
}());
*/

obfuscate(sourceCode, options)

Returns ObfuscationResult object which contains two public methods:

  • getObfuscatedCode() - returns string with obfuscated code;
  • getSourceMap() - if sourceMap option is enabled - returns string with source map or an empty string if sourceMapMode option is set as inline;
  • getIdentifierNamesCache() - returns object with identifier names cache if identifierNamesCache option is enabled, null overwise.

Calling toString() for ObfuscationResult object will return string with obfuscated code.

Method takes two parameters, sourceCode and options – the source code and the options respectively:

  • sourceCode (string, default: null) – any valid source code, passed as a string;
  • options (Object, default: null) – an object with options.

For available options, see options.

obfuscateMultiple(sourceCodesObject, options)

Accepts sourceCodesObject that is a map which keys are identifiers of source codes and values are source codes:

{
    foo: 'var foo = 1;',
    bar: 'var bar = 2;'
}

Returns a map object which keys are identifiers of source codes and values are ObfuscationResult objects.

getOptionsByPreset(optionsPreset)

Returns an options object for the passed options preset name.

CLI usage

See CLI options.

Obfuscate single file

Usage:

javascript-obfuscator input_file_name.js [options]
javascript-obfuscator input_file_name.js --output output_file_name.js [options]
javascript-obfuscator input_file_name.js --output output_folder_name [options]
javascript-obfuscator input_folder_name --output output_folder_name [options]

Obfuscation of single input file with .js extension.

If the destination path is not specified with the --output option, the obfuscated file will be saved into the input file directory, with INPUT_FILE_NAME-obfuscated.js name.

Some examples:

javascript-obfuscator samples/sample.js --compact true --self-defending false
// creates a new file samples/sample-obfuscated.js

javascript-obfuscator samples/sample.js --output output/output.js --compact true --self-defending false
// creates a new file output/output.js

Obfuscate directory recursively

Usage:

javascript-obfuscator ./dist [options]
// creates a new obfuscated files under `./dist` directory near the input files with `obfuscated` postfix

javascript-obfuscator ./dist --output ./dist/obfuscated [options]
// creates a folder structure with obfuscated files under `./dist/obfuscated` path

Obfuscation of all .js files under input directory. If this directory contains already obfuscated files with -obfuscated postfix - these files will ignored.

Obfuscated files will saved into the input directory under INPUT_FILE_NAME-obfuscated.js name.

Conditional comments

You can disable and enable obfuscation for specific parts of the code by adding following comments:

  • disable: // javascript-obfuscator:disable or /* javascript-obfuscator:disable */;
  • enable: // javascript-obfuscator:enable or /* javascript-obfuscator:enable */.

Example:

// input
var foo = 1;
// javascript-obfuscator:disable
var bar = 2;

// output
var _0xabc123 = 0x1;
var bar = 2;

Conditional comments affect only direct transformations of AST-tree nodes. All child transformations still will be applied to the AST-tree nodes.

For example:

  • Obfuscation of the variable's name at its declaration is called direct transformation;
  • Obfuscation of the variable's name beyond its declaration is called child transformation.

Kind of variables

Kind of variables of inserted nodes will auto-detected, based on most prevailing kind of variables of source code.

Conflicts of identifier names between different files

During obfuscation of the different files, the same names can be generated for the global identifiers between these files. To prevent this set the unique prefix for all global identifiers for each obfuscated file with identifiersPrefix option.

When using CLI this prefix will be added automatically.

JavaScript Obfuscator Options

Following options are available for the JS Obfuscator:

options:

{
    compact: true,
    controlFlowFlattening: false,
    controlFlowFlatteningThreshold: 0.75,
    deadCodeInjection: false,
    deadCodeInjectionThreshold: 0.4,
    debugProtection: false,
    debugProtectionInterval: 0,
    disableConsoleOutput: false,
    domainLock: [],
    domainLockRedirectUrl: 'about:blank',
    forceTransformStrings: [],
    identifierNamesCache: null,
    identifierNamesGenerator: 'hexadecimal',
    identifiersDictionary: [],
    identifiersPrefix: '',
    ignoreImports: false,
    inputFileName: '',
    log: false,
    numbersToExpressions: false,
    optionsPreset: 'default',
    renameGlobals: false,
    renameProperties: false,
    renamePropertiesMode: 'safe',
    reservedNames: [],
    reservedStrings: [],
    seed: 0,
    selfDefending: false,
    simplify: true,
    sourceMap: false,
    sourceMapBaseUrl: '',
    sourceMapFileName: '',
    sourceMapMode: 'separate',
    sourceMapSourcesMode: 'sources-content',
    splitStrings: false,
    splitStringsChunkLength: 10,
    stringArray: true,
    stringArrayCallsTransform: true,
    stringArrayCallsTransformThreshold: 0.5,
    stringArrayEncoding: [],
    stringArrayIndexesType: [
        'hexadecimal-number'
    ],
    stringArrayIndexShift: true,
    stringArrayRotate: true,
    stringArrayShuffle: true,
    stringArrayWrappersCount: 1,
    stringArrayWrappersChainedCalls: true,
    stringArrayWrappersParametersMaxCount: 2,
    stringArrayWrappersType: 'variable',
    stringArrayThreshold: 0.75,
    target: 'browser',
    transformObjectKeys: false,
    unicodeEscapeSequence: false
}

CLI options:

    -v, --version
    -h, --help

    -o, --output

    --compact <boolean>
    --config <string>
    --control-flow-flattening <boolean>
    --control-flow-flattening-threshold <number>
    --dead-code-injection <boolean>
    --dead-code-injection-threshold <number>
    --debug-protection <boolean>
    --debug-protection-interval <number>
    --disable-console-output <boolean>
    --domain-lock '<list>' (comma separated)
    --domain-lock-redirect-url <string>
    --exclude '<list>' (comma separated)
    --force-transform-strings '<list>' (comma separated)
    --identifier-names-cache-path <string>
    --identifier-names-generator <string> [dictionary, hexadecimal, mangled, mangled-shuffled]
    --identifiers-dictionary '<list>' (comma separated)
    --identifiers-prefix <string>
    --ignore-imports <boolean>
    --log <boolean>
    --numbers-to-expressions <boolean>
    --options-preset <string> [default, low-obfuscation, medium-obfuscation, high-obfuscation]
    --rename-globals <boolean>
    --rename-properties <boolean>
    --rename-properties-mode <string> [safe, unsafe]
    --reserved-names '<list>' (comma separated)
    --reserved-strings '<list>' (comma separated)
    --seed <string|number>
    --self-defending <boolean>
    --simplify <boolean>
    --source-map <boolean>
    --source-map-base-url <string>
    --source-map-file-name <string>
    --source-map-mode <string> [inline, separate]
    --source-map-sources-mode <string> [sources, sources-content]
    --split-strings <boolean>
    --split-strings-chunk-length <number>
    --string-array <boolean>
    --string-array-calls-transform <boolean>
    --string-array-calls-transform-threshold <number>
    --string-array-encoding '<list>' (comma separated) [none, base64, rc4]
    --string-array-indexes-type '<list>' (comma separated) [hexadecimal-number, hexadecimal-numeric-string]
    --string-array-index-shift <boolean>
    --string-array-rotate <boolean>
    --string-array-shuffle <boolean>
    --string-array-wrappers-count <number>
    --string-array-wrappers-chained-calls <boolean>
    --string-array-wrappers-parameters-max-count <number>
    --string-array-wrappers-type <string> [variable, function]
    --string-array-threshold <number>
    --target <string> [browser, browser-no-eval, node]
    --transform-object-keys <boolean>
    --unicode-escape-sequence <boolean>

compact

Type: boolean Default: true

Compact code output on one line.

config

Type: string Default: ``

Name of JS/JSON config file which contains obfuscator options. These will be overridden by options passed directly to CLI

controlFlowFlattening

Type: boolean Default: false

⚠️ This option greatly affects the performance up to 1.5x slower runtime speed. Use controlFlowFlatteningThreshold to set percentage of nodes that will affected by control flow flattening.

Enables code control flow flattening. Control flow flattening is a structure transformation of the source code that hinders program comprehension.

Example:

// input
(function(){
    function foo () {
        return function () {
            var sum = 1 + 2;
            console.log(1);
            console.log(2);
            console.log(3);
            console.log(4);
            console.log(5);
            console.log(6);
        }
    }
    
    foo()();
})();

// output
(function () {
    function _0x3bfc5c() {
        return function () {
            var _0x3260a5 = {
                'WtABe': '4|0|6|5|3|2|1',
                'GokKo': function _0xf87260(_0x427a8e, _0x43354c) {
                    return _0x427a8e + _0x43354c;
                }
            };
            var _0x1ad4d6 = _0x3260a5['WtABe']['split']('|'), _0x1a7b12 = 0x0;
            while (!![]) {
                switch (_0x1ad4d6[_0x1a7b12++]) {
                case '0':
                    console['log'](0x1);
                    continue;
                case '1':
                    console['log'](0x6);
                    continue;
                case '2':
                    console['log'](0x5);
                    continue;
                case '3':
                    console['log'](0x4);
                    continue;
                case '4':
                    var _0x1f2f2f = _0x3260a5['GokKo'](0x1, 0x2);
                    continue;
                case '5':
                    console['log'](0x3);
                    continue;
                case '6':
                    console['log'](0x2);
                    continue;
                }
                break;
            }
        };
    }

	_0x3bfc5c()();
}());

controlFlowFlatteningThreshold

Type: number Default: 0.75 Min: 0 Max: 1

The probability that the controlFlowFlattening transformation will be applied to any given node.

This setting is especially useful for large code size because large amounts of control flow transformations can slow down your code and increase code size.

controlFlowFlatteningThreshold: 0 equals to controlFlowFlattening: false.

deadCodeInjection

Type: boolean Default: false

⚠️ Dramatically increases size of obfuscated code (up to 200%), use only if size of obfuscated code doesn't matter. Use deadCodeInjectionThreshold to set percentage of nodes that will affected by dead code injection.
⚠️ This option forcibly enables stringArray option.

With this option, random blocks of dead code will be added to the obfuscated code.

Example:

// input
(function(){
    if (true) {
        var foo = function () {
            console.log('abc');
        };
        var bar = function () {
            console.log('def');
        };
        var baz = function () {
            console.log('ghi');
        };
        var bark = function () {
            console.log('jkl');
        };
        var hawk = function () {
            console.log('mno');
        };

        foo();
        bar();
        baz();
        bark();
        hawk();
    }
})();

// output
var _0x37b8 = [
    'YBCtz',
    'GlrkA',
    'urPbb',
    'abc',
    'NMIhC',
    'yZgAj',
    'zrAId',
    'EtyJA',
    'log',
    'mno',
    'jkl',
    'def',
    'Quzya',
    'IWbBa',
    'ghi'
];
function _0x43a7(_0x12cf56, _0x587376) {
    _0x43a7 = function (_0x2f87a8, _0x47eac2) {
        _0x2f87a8 = _0x2f87a8 - (0x16a7 * 0x1 + 0x5 * 0x151 + -0x1c92);
        var _0x341e03 = _0x37b8[_0x2f87a8];
        return _0x341e03;
    };
    return _0x43a7(_0x12cf56, _0x587376);
}
(function () {
    if (!![]) {
        var _0xbbe28f = function () {
            var _0x2fc85f = _0x43a7;
            if (_0x2fc85f(0xaf) === _0x2fc85f(0xae)) {
                _0x1dd94f[_0x2fc85f(0xb2)](_0x2fc85f(0xb5));
            } else {
                console[_0x2fc85f(0xb2)](_0x2fc85f(0xad));
            }
        };
        var _0x5e46bc = function () {
            var _0x15b472 = _0x43a7;
            if (_0x15b472(0xb6) !== _0x15b472(0xaa)) {
                console[_0x15b472(0xb2)](_0x15b472(0xb5));
            } else {
                _0x47eac2[_0x15b472(0xb2)](_0x15b472(0xad));
            }
        };
        var _0x3669e8 = function () {
            var _0x47a442 = _0x43a7;
            if (_0x47a442(0xb7) !== _0x47a442(0xb0)) {
                console[_0x47a442(0xb2)](_0x47a442(0xb8));
            } else {
                _0x24e0bf[_0x47a442(0xb2)](_0x47a442(0xb3));
            }
        };
        var _0x28b05a = function () {
            var _0x497902 = _0x43a7;
            if (_0x497902(0xb1) === _0x497902(0xb1)) {
                console[_0x497902(0xb2)](_0x497902(0xb4));
            } else {
                _0x59c9c6[_0x497902(0xb2)](_0x497902(0xb4));
            }
        };
        var _0x402a54 = function () {
            var _0x1906b7 = _0x43a7;
            if (_0x1906b7(0xab) === _0x1906b7(0xac)) {
                _0xb89cd0[_0x1906b7(0xb2)](_0x1906b7(0xb8));
            } else {
                console[_0x1906b7(0xb2)](_0x1906b7(0xb3));
            }
        };
        _0xbbe28f();
        _0x5e46bc();
        _0x3669e8();
        _0x28b05a();
        _0x402a54();
    }
}());

deadCodeInjectionThreshold

Type: number Default: 0.4 Min: 0 Max: 1

Allows to set percentage of nodes that will affected by deadCodeInjection.

debugProtection

Type: boolean Default: false

⚠️ Can freeze your browser if you open the Developer Tools.

This option makes it almost impossible to use the debugger function of the Developer Tools (both on WebKit-based and Mozilla Firefox).

debugProtectionInterval

Type: number Default: 0

⚠️ Can freeze your browser! Use at own risk.

If set, an interval in milliseconds is used to force the debug mode on the Console tab, making it harder to use other features of the Developer Tools. Works if debugProtection is enabled. Recommended value is between 2000 and 4000 milliseconds.

disableConsoleOutput

Type: boolean Default: false

⚠️ This option disables console calls globally for all scripts

Disables the use of console.log, console.info, console.error, console.warn, console.debug, console.exception and console.trace by replacing them with empty functions. This makes the use of the debugger harder.

domainLock

Type: string[] Default: []

⚠️ This option does not work with target: 'node'

Allows to run the obfuscated source code only on specific domains and/or sub-domains. This makes really hard for someone to just copy and paste your source code and run it elsewhere.

If the source code isn't run on the domains specified by this option, the browser will be redirected to a passed to the domainLockRedirectUrl option URL.

Multiple domains and sub-domains

It's possible to lock your code to more than one domain or sub-domain. For instance, to lock it so the code only runs on www.example.com add www.example.com. To make it work on the root domain including any sub-domains (example.com, sub.example.com), use .example.com.

domainLockRedirectUrl

Type: string Default: about:blank

⚠️ This option does not work with target: 'node'

Allows the browser to be redirected to a passed URL if the source code isn't run on the domains specified by domainLock

exclude

Type: string[] Default: []

A file names or globs which indicates files to exclude from obfuscation.

forceTransformStrings

Type: string[] Default: []

Enables force transformation of string literals, which being matched by passed RegExp patterns.

⚠️ This option affects only strings that shouldn't be transformed by stringArrayThreshold (or possible other thresholds in the future)

The option has a priority over reservedStrings option but hasn't a priority over conditional comments.

Example:

	{
		forceTransformStrings: [
			'some-important-value',
			'some-string_\d'
		]
	}

identifierNamesCache

Type: Object | null Default: null

The main goal for this option is the ability to use the same identifier names during obfuscation of multiple sources/files.

Currently the two types of the identifiers are supported:

  • Global identifiers:
    • All global identifiers will be written to the cache;
    • All matched undeclared global identifiers will be replaced by the values from the cache.
  • Property identifiers, only when renameProperties option is enabled:
    • All property identifiers will be written to the cache;
    • All matched property identifiers will be replaced by the values from the cache.

Node.js API

If a null value is passed, completely disables the cache.

If an empty object ({}) is passed, enables the writing identifier names to the cache-object (TIdentifierNamesCache type). This cache-object will be accessed through the getIdentifierNamesCache method call of ObfuscationResult object.

The resulting cache-object can be next used as identifierNamesGenerator option value for using these names during obfuscation of all matched identifier names of next sources.

Example:

const source1ObfuscationResult = JavaScriptObfuscator.obfuscate(
    `
        function foo(arg) {
           console.log(arg)
        }
        
        function bar() {
            var bark = 2;
        }
    `,
    {
        compact: false,
        identifierNamesCache: {},
        renameGlobals: true
    }
)

console.log(source1ObfuscationResult.getIdentifierNamesCache());
/*
    { 
        globalIdentifiers: {
            foo: '_0x5de86d',
            bar: '_0x2a943b'
        }
    }
*/



const source2ObfuscationResult = JavaScriptObfuscator.obfuscate(
    `
        // Expecting that these global functions are defined in another obfuscated file
        foo(1);
        bar();
        
        // Expecting that this global function is defined in third-party package
        baz();
    `,
    {
        compact: false,
        identifierNamesCache: source1ObfuscationResult.getIdentifierNamesCache(),
        renameGlobals: true
    }
)

console.log(source2ObfuscationResult.getObfuscatedCode());
/*
    _0x5de86d(0x1);
    _0x2a943b();
    baz();
 */

CLI

CLI has a different option --identifier-names-cache-path that allows defining a path to the existing .json file that will be used to read and write identifier names cache.

If a path to the empty file will be passed - identifier names cache will be written to that file.

This file with existing cache can be used again as --identifier-names-cache-path option value for using these names during obfuscation of all matched identifier names of the next files.

identifierNamesGenerator

Type: string Default: hexadecimal

Sets identifier names generator.

Available values:

  • dictionary: identifier names from identifiersDictionary list
  • hexadecimal: identifier names like _0xabc123
  • mangled: short identifier names like a, b, c
  • mangled-shuffled: same as mangled but with shuffled alphabet

identifiersDictionary

Type: string[] Default: []

Sets identifiers dictionary for identifierNamesGenerator: dictionary option. Each identifier from the dictionary will be used in a few variants with a different casing of each character. Thus, the number of identifiers in the dictionary should depend on the identifiers amount at original source code.

identifiersPrefix

Type: string Default: ''

Sets prefix for all global identifiers.

Use this option when you want to obfuscate multiple files. This option helps to avoid conflicts between global identifiers of these files. Prefix should be different for every file.

ignoreImports

Type: boolean Default: false

Prevents obfuscation of require imports. Could be helpful in some cases when for some reason runtime environment requires these imports with static strings only.

inputFileName

Type: string Default: ''

Allows to set name of the input file with source code. This name will be used internally for source map generation. Required when using NodeJS API and sourceMapSourcesMode option has sources value`.

log

Type: boolean Default: false

Enables logging of the information to the console.

numbersToExpressions

Type: boolean Default: false

Enables numbers conversion to expressions

Example:

// input
const foo = 1234;

// output
const foo=-0xd93+-0x10b4+0x41*0x67+0x84e*0x3+-0xff8;

optionsPreset

Type: string Default: default

Allows to set options preset.

Available values:

  • default;
  • low-obfuscation;
  • medium-obfuscation;
  • high-obfuscation.

All addition options will be merged with selected options preset.

renameGlobals

Type: boolean Default: false

⚠️ this option can break your code. Enable it only if you know what it does!

Enables obfuscation of global variable and function names with declaration.

renameProperties

Type: boolean Default: false

⚠️ this option MAY break your code. Enable it only if you know what it does!

Enables renaming of property names. All built-in DOM properties and properties in core JavaScript classes will be ignored.

To switch between safe and unsafe modes of this option use renamePropertiesMode option.

To set format of renamed property names use identifierNamesGenerator option.

To control which properties will be renamed use reservedNames option.

Example:

// input
(function () {
    const foo = {
        prop1: 1,
        prop2: 2,
        calc: function () {
            return this.prop1 + this.prop2;
        }
    };
    
    console.log(foo.calc());
})();

// output
(function () {
    const _0x46529b = {
        '_0x10cec7': 0x1,
        '_0xc1c0ca': 0x2,
        '_0x4b961d': function () {
            return this['_0x10cec7'] + this['_0xc1c0ca'];
        }
    };
    console['log'](_0x46529b['_0x4b961d']());
}());

renamePropertiesMode

Type: string Default: safe

⚠️ Even in safe mode, renameProperties option MAY break your code.

Specifies renameProperties option mode:

  • safe - default behaviour after 2.11.0 release. Trying to rename properties in a more safe way to prevent runtime errors. With this mode some properties will be excluded from renaming.
  • unsafe - default behaviour before 2.11.0 release. Renames properties in an unsafe way without any restrictions.

If one file is using properties from other file, use identifierNamesCache option to keep the same property names between these files.

reservedNames

Type: string[] Default: []

Disables obfuscation and generation of identifiers, which being matched by passed RegExp patterns.

Example:

	{
		reservedNames: [
			'^someVariable',
			'functionParameter_\d'
		]
	}

reservedStrings

Type: string[] Default: []

Disables transformation of string literals, which being matched by passed RegExp patterns.

Example:

	{
		reservedStrings: [
			'react-native',
			'\.\/src\/test',
			'some-string_\d'
		]
	}

seed

Type: string|number Default: 0

This option sets seed for random generator. This is useful for creating repeatable results.

If seed is 0 - random generator will work without seed.

selfDefending

Type: boolean Default: false

⚠️ Don't change obfuscated code in any way after obfuscation with this option, because any change like uglifying of code can trigger self defending and code wont work anymore!
⚠️ This option forcibly sets compact value to true

This option makes the output code resilient against formatting and variable renaming. If one tries to use a JavaScript beautifier on the obfuscated code, the code won't work anymore, making it harder to understand and modify it.

simplify

Type: boolean Default: true

Enables additional code obfuscation through simplification.

⚠️ in future releases obfuscation of boolean literals (true => !![]) will be moved under this option.

Example:

// input
if (condition1) {
    const foo = 1;
    const bar = 2;
  
    console.log(foo);
  
    return bar;
} else if (condition2) {
    console.log(1);
    console.log(2);
    console.log(3);
  
    return 4;
} else {
    return 5;
}

// output
if (condition1) {
    const foo = 0x1, bar = 0x2;
    return console['log'](foo), bar;
} else
    return condition2 ? (console['log'](0x1), console['log'](0x2), console['log'](0x3), 0x4) : 0x5;

sourceMap

Type: boolean Default: false

Enables source map generation for obfuscated code.

Source maps can be useful to help you debug your obfuscated JavaScript source code. If you want or need to debug in production, you can upload the separate source map file to a secret location and then point your browser there.

sourceMapBaseUrl

Type: string Default: ``

Sets base url to the source map import url when sourceMapMode: 'separate'.

CLI example:

javascript-obfuscator input.js --output out.js --source-map true --source-map-base-url 'http://localhost:9000'

Result:

//# sourceMappingURL=http://localhost:9000/out.js.map

sourceMapFileName

Type: string Default: ``

Sets file name for output source map when sourceMapMode: 'separate'.

CLI example:

javascript-obfuscator input.js --output out.js --source-map true --source-map-base-url 'http://localhost:9000' --source-map-file-name example

Result:

//# sourceMappingURL=http://localhost:9000/example.js.map

sourceMapMode

Type: string Default: separate

Specifies source map generation mode:

  • inline - add source map at the end of each .js files;
  • separate - generates corresponding '.map' file with source map. In case you run obfuscator through CLI - adds link to source map file to the end of file with obfuscated code //# sourceMappingUrl=file.js.map.

sourceMapSourcesMode

Type: string Default: sources-content

Allows to control sources and sourcesContent fields of the source map:

  • sources-content - adds dummy sources field, adds sourcesContent field with the original source code;
  • sources - adds sources field with a valid source description, does not add sourcesContent field. When using NodeJS API it's required to define inputFileName option that will be used as sources field value.

splitStrings

Type: boolean Default: false

Splits literal strings into chunks with length of splitStringsChunkLength option value.

Example:

// input
(function(){
    var test = 'abcdefg';
})();

// output
(function(){
    var _0x5a21 = 'ab' + 'cd' + 'ef' + 'g';
})();

splitStringsChunkLength

Type: number Default: 10

Sets chunk length of splitStrings option.

stringArray

Type: boolean Default: true

Removes string literals and place them in a special array. For instance, the string "Hello World" in var m = "Hello World"; will be replaced with something like var m = _0x12c456[0x1];

stringArrayCallsTransform

Type: boolean Default: false

⚠️ stringArray option must be enabled

Enables the transformation of calls to the stringArray. All arguments of these calls may be extracted to a different object depending on stringArrayCallsTransformThreshold value. So it makes it even harder to automatically find calls to the string array.

Example:

function foo() {
    var k = {
        c: 0x2f2,
        d: '0x396',
        e: '0x397',
        f: '0x39a',
        g: '0x39d',
        h: 0x398,
        l: 0x394,
        m: '0x39b',
        n: '0x39f',
        o: 0x395,
        p: 0x395,
        q: 0x399,
        r: '0x399'
    };
    var c = i(k.d, k.e);
    var d = i(k.f, k.g);
    var e = i(k.h, k.l);
    var f = i(k.m, k.n);
    function i(c, d) {
        return b(c - k.c, d);
    }
    var g = i(k.o, k.p);
    var h = i(k.q, k.r);
}
function j(c, d) {
    var l = { c: 0x14b };
    return b(c - -l.c, d);
}
console[j(-'0xa6', -'0xa6')](foo());
function b(c, d) {
    var e = a();
    b = function (f, g) {
        f = f - 0xa3;
        var h = e[f];
        return h;
    };
    return b(c, d);
}
function a() {
    var m = [
        'string5',
        'string1',
        'log',
        'string3',
        'string6',
        'string2',
        'string4'
    ];
    a = function () {
        return m;
    };
    return a();
}

stringArrayCallsTransformThreshold

Type: number Default: 0.5

⚠️ stringArray and stringArrayCallsTransformThreshold options must be enabled

You can use this setting to adjust the probability (from 0 to 1) that calls to the string array will be transformed.

stringArrayEncoding

Type: string[] Default: []

⚠️ stringArray option must be enabled

This option can slow down your script.

Encode all string literals of the stringArray using base64 or rc4 and inserts a special code that used to decode it back at runtime.

Each stringArray value will be encoded by the randomly picked encoding from the passed list. This makes possible to use multiple encodings.

Available values:

  • 'none' (boolean): doesn't encode stringArray value
  • 'base64' (string): encodes stringArray value using base64
  • 'rc4' (string): encodes stringArray value using rc4. About 30-50% slower than base64, but more harder to get initial values. It's recommended to disable unicodeEscapeSequence option when using rc4 encoding to prevent very large size of obfuscated code.

For example with the following option values some stringArray value won't be encoded, and some values will be encoded with base64 and rc4 encoding:

stringArrayEncoding: [
    'none',
    'base64',
    'rc4'
]

stringArrayIndexesType

Type: string[] Default: ['hexadecimal-number']

⚠️ stringArray option must be enabled

Allows to control the type of string array call indexes.

Each stringArray call index will be transformed by the randomly picked type from the passed list. This makes possible to use multiple types.

Available values:

  • 'hexadecimal-number' (default): transforms string array call indexes as hexadecimal numbers
  • 'hexadecimal-numeric-string': transforms string array call indexes as hexadecimal numeric string

Before 2.9.0 release javascript-obfuscator transformed all string array call indexes with hexadecimal-numeric-string type. This makes some manual deobfuscation slightly harder but it allows easy detection of these calls by automatic deobfuscators.

The new hexadecimal-number type approaches to make harder auto-detect of string array call patterns in the code.

More types will be added in the future.

stringArrayIndexShift

Type: boolean Default: true

⚠️ stringArray option must be enabled

Enables additional index shift for all string array calls

stringArrayRotate

Type: boolean Default: true

⚠️ stringArray must be enabled

Shift the stringArray array by a fixed and random (generated at the code obfuscation) places. This makes it harder to match the order of the removed strings to their original place.

stringArrayShuffle

Type: boolean Default: true

⚠️ stringArray must be enabled

Randomly shuffles the stringArray array items.

stringArrayWrappersCount

Type: number Default: 1

⚠️ stringArray option must be enabled

Sets the count of wrappers for the string array inside each root or function scope. The actual count of wrappers inside each scope is limited by a count of literal nodes within this scope.

Example:

// Input
const foo = 'foo';
const bar = 'bar';
        
function test () {
    const baz = 'baz';
    const bark = 'bark';
    const hawk = 'hawk';
}

const eagle = 'eagle';

// Output, stringArrayWrappersCount: 5
const _0x3f6c = [
    'bark',
    'bar',
    'foo',
    'eagle',
    'hawk',
    'baz'
];
const _0x48f96e = _0x2e13;
const _0x4dfed8 = _0x2e13;
const _0x55e970 = _0x2e13;
function _0x2e13(_0x33c4f5, _0x3f6c62) {
    _0x2e13 = function (_0x2e1388, _0x60b1e) {
        _0x2e1388 = _0x2e1388 - 0xe2;
        let _0x53d475 = _0x3f6c[_0x2e1388];
        return _0x53d475;
    };
    return _0x2e13(_0x33c4f5, _0x3f6c62);
}
const foo = _0x48f96e(0xe4);
const bar = _0x4dfed8(0xe3);
function test() {
    const _0x1c262f = _0x2e13;
    const _0x54d7a4 = _0x2e13;
    const _0x5142fe = _0x2e13;
    const _0x1392b0 = _0x1c262f(0xe7);
    const _0x201a58 = _0x1c262f(0xe2);
    const _0xd3a7fb = _0x1c262f(0xe6);
}
const eagle = _0x48f96e(0xe5);

stringArrayWrappersChainedCalls

Type: boolean Default: true

⚠️ stringArray and stringArrayWrappersCount options must be enabled

Enables the chained calls between string array wrappers.

Example:

// Input
const foo = 'foo';
const bar = 'bar';
        
function test () {
    const baz = 'baz';
    const bark = 'bark';

    function test1() {
        const hawk = 'hawk';
        const eagle = 'eagle';
    } 
}

// Output, stringArrayWrappersCount: 5, stringArrayWrappersChainedCalls: true
const _0x40c2 = [
    'bar',
    'bark',
    'hawk',
    'eagle',
    'foo',
    'baz'
];
const _0x31c087 = _0x3280;
const _0x31759a = _0x3280;
function _0x3280(_0x1f52ee, _0x40c2a2) {
    _0x3280 = function (_0x3280a4, _0xf07b02) {
        _0x3280a4 = _0x3280a4 - 0x1c4;
        let _0x57a182 = _0x40c2[_0x3280a4];
        return _0x57a182;
    };
    return _0x3280(_0x1f52ee, _0x40c2a2);
}
const foo = _0x31c087(0x1c8);
const bar = _0x31c087(0x1c4);
function test() {
    const _0x848719 = _0x31759a;
    const _0x2693bf = _0x31c087;
    const _0x2c08e8 = _0x848719(0x1c9);
    const _0x359365 = _0x2693bf(0x1c5);
    function _0x175e90() {
        const _0x310023 = _0x848719;
        const _0x2302ef = _0x2693bf;
        const _0x237437 = _0x310023(0x1c6);
        const _0x56145c = _0x310023(0x1c7);
    }
}

stringArrayWrappersParametersMaxCount

Type: number Default: 2

⚠️ stringArray option must be enabled
⚠️ Currently this option affects only wrappers added by stringArrayWrappersType function option value

Allows to control the maximum number of string array wrappers parameters. Default and minimum value is 2. Recommended value between 2 and 5.

stringArrayWrappersType

Type: string Default: variable

⚠️ stringArray and stringArrayWrappersCount options must be enabled

Allows to select a type of the wrappers that are appending by the stringArrayWrappersCount option.

Available values:

  • 'variable': appends variable wrappers at the top of each scope. Fast performance.
  • 'function': appends function wrappers at random positions inside each scope. Slower performance than with variable but provides more strict obfuscation.

Highly recommended to use function wrappers for higher obfuscation when a performance loss doesn't have a high impact on an obfuscated application.

Example of the 'function' option value:

// input
const foo = 'foo';

function test () {
    const bar = 'bar';
    console.log(foo, bar);
}

test();

// output
const a = [
    'log',
    'bar',
    'foo'
];
const foo = d(0x567, 0x568);
function b(c, d) {
    b = function (e, f) {
        e = e - 0x185;
        let g = a[e];
        return g;
    };
    return b(c, d);
}
function test() {
    const c = e(0x51c, 0x51b);
    function e (c, g) {
        return b(c - 0x396, g);
    }
    console[f(0x51b, 0x51d)](foo, c);
    function f (c, g) {
        return b(c - 0x396, g);
    }
}
function d (c, g) {
    return b(g - 0x3e1, c);
}
test();

stringArrayThreshold

Type: number Default: 0.8 Min: 0 Max: 1

⚠️ stringArray option must be enabled

You can use this setting to adjust the probability (from 0 to 1) that a string literal will be inserted into the stringArray.

This setting is especially useful for large code size because it repeatedly calls to the string array and can slow down your code.

stringArrayThreshold: 0 equals to stringArray: false.

target

Type: string Default: browser

Allows to set target environment for obfuscated code.

Available values:

  • browser;
  • browser-no-eval;
  • node.

Currently output code for browser and node targets is identical, but some browser-specific options are not allowed to use with node target. Output code for browser-no-eval target is not using eval.

transformObjectKeys

Type: boolean Default: false

Enables transformation of object keys.

Example:

// input
(function(){
    var object = {
        foo: 'test1',
        bar: {
            baz: 'test2'
        }
    };
})();

// output
var _0x4735 = [
    'foo',
    'baz',
    'bar',
    'test1',
    'test2'
];
function _0x390c(_0x33d6b6, _0x4735f4) {
    _0x390c = function (_0x390c37, _0x1eed85) {
        _0x390c37 = _0x390c37 - 0x198;
        var _0x2275f8 = _0x4735[_0x390c37];
        return _0x2275f8;
    };
    return _0x390c(_0x33d6b6, _0x4735f4);
}
(function () {
    var _0x17d1b7 = _0x390c;
    var _0xc9b6bb = {};
    _0xc9b6bb[_0x17d1b7(0x199)] = _0x17d1b7(0x19c);
    var _0x3d959a = {};
    _0x3d959a[_0x17d1b7(0x198)] = _0x17d1b7(0x19b);
    _0x3d959a[_0x17d1b7(0x19a)] = _0xc9b6bb;
    var _0x41fd86 = _0x3d959a;
}());

unicodeEscapeSequence

Type: boolean Default: false

Allows to enable/disable string conversion to unicode escape sequence.

Unicode escape sequence increases code size greatly and strings easily can be reverted to their original view. Recommended to enable this option only for small source code.

Preset Options

High obfuscation, low performance

The performance will be much slower than without obfuscation

{
    compact: true,
    controlFlowFlattening: true,
    controlFlowFlatteningThreshold: 1,
    deadCodeInjection: true,
    deadCodeInjectionThreshold: 1,
    debugProtection: true,
    debugProtectionInterval: 4000,
    disableConsoleOutput: true,
    identifierNamesGenerator: 'hexadecimal',
    log: false,
    numbersToExpressions: true,
    renameGlobals: false,
    selfDefending: true,
    simplify: true,
    splitStrings: true,
    splitStringsChunkLength: 5,
    stringArray: true,
    stringArrayCallsTransform: true,
    stringArrayEncoding: ['rc4'],
    stringArrayIndexShift: true,
    stringArrayRotate: true,
    stringArrayShuffle: true,
    stringArrayWrappersCount: 5,
    stringArrayWrappersChainedCalls: true,    
    stringArrayWrappersParametersMaxCount: 5,
    stringArrayWrappersType: 'function',
    stringArrayThreshold: 1,
    transformObjectKeys: true,
    unicodeEscapeSequence: false
}

Medium obfuscation, optimal performance

The performance will be slower than without obfuscation

{
    compact: true,
    controlFlowFlattening: true,
    controlFlowFlatteningThreshold: 0.75,
    deadCodeInjection: true,
    deadCodeInjectionThreshold: 0.4,
    debugProtection: false,
    debugProtectionInterval: 0,
    disableConsoleOutput: true,
    identifierNamesGenerator: 'hexadecimal',
    log: false,
    numbersToExpressions: true,
    renameGlobals: false,
    selfDefending: true,
    simplify: true,
    splitStrings: true,
    splitStringsChunkLength: 10,
    stringArray: true,
    stringArrayCallsTransform: true,
    stringArrayCallsTransformThreshold: 0.75,
    stringArrayEncoding: ['base64'],
    stringArrayIndexShift: true,
    stringArrayRotate: true,
    stringArrayShuffle: true,
    stringArrayWrappersCount: 2,
    stringArrayWrappersChainedCalls: true,
    stringArrayWrappersParametersMaxCount: 4,
    stringArrayWrappersType: 'function',
    stringArrayThreshold: 0.75,
    transformObjectKeys: true,
    unicodeEscapeSequence: false
}

Low obfuscation, High performance

The performance will be at a relatively normal level

{
    compact: true,
    controlFlowFlattening: false,
    deadCodeInjection: false,
    debugProtection: false,
    debugProtectionInterval: 0,
    disableConsoleOutput: true,
    identifierNamesGenerator: 'hexadecimal',
    log: false,
    numbersToExpressions: false,
    renameGlobals: false,
    selfDefending: true,
    simplify: true,
    splitStrings: false,
    stringArray: true,
    stringArrayCallsTransform: false,
    stringArrayEncoding: [],
    stringArrayIndexShift: true,
    stringArrayRotate: true,
    stringArrayShuffle: true,
    stringArrayWrappersCount: 1,
    stringArrayWrappersChainedCalls: true,
    stringArrayWrappersParametersMaxCount: 2,
    stringArrayWrappersType: 'variable',
    stringArrayThreshold: 0.75,
    unicodeEscapeSequence: false
}

Default preset, High performance

{
    compact: true,
    controlFlowFlattening: false,
    deadCodeInjection: false,
    debugProtection: false,
    debugProtectionInterval: 0,
    disableConsoleOutput: false,
    identifierNamesGenerator: 'hexadecimal',
    log: false,
    numbersToExpressions: false,
    renameGlobals: false,
    selfDefending: false,
    simplify: true,
    splitStrings: false,
    stringArray: true,
    stringArrayCallsTransform: false,
    stringArrayCallsTransformThreshold: 0.5,
    stringArrayEncoding: [],
    stringArrayIndexShift: true,
    stringArrayRotate: true,
    stringArrayShuffle: true,
    stringArrayWrappersCount: 1,
    stringArrayWrappersChainedCalls: true,
    stringArrayWrappersParametersMaxCount: 2,
    stringArrayWrappersType: 'variable',
    stringArrayThreshold: 0.75,
    unicodeEscapeSequence: false
}

Frequently Asked Questions

What javascript versions are supported?

es3, es5, es2015, es2016, es2017, es2018, es2019 and partially es2020

I want to use feature that described in README.md but it's not working!

The README on the master branch might not match that of the latest stable release.

Why CLI command not working?

Try to run npm link javascript-obfuscator command or install it globally with npm i -g javascript-obfuscator

Online version?

obfuscator.io

JSX support?

No. JSX support isn't planned.

How to change kind of variables of inserted nodes (var, let or const)?

See: Kind of variables

Why I got null value instead of BigInt number?

BigInt obfuscation works correctly only in environments that support BigInt values. See ESTree spec

I enabled renameProperties option, and my code broke! What to do?

Try renamePropertiesMode: 'safe' option, if it still doesn't work, just disable this option.

Backers

Support us with a monthly donation and help us continue our activities. [Become a backer]

Sponsors

Become a sponsor and get your logo on our README on Github with a link to your site.

License

FOSSA Status

Copyright (C) 2016-2022 Timofey Kachalov.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

  • Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
  • Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

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