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JavaScript Obfuscator Online — Protect JS Source Code Free

A free JavaScript obfuscator that transforms readable source code into a functionally equivalent but difficult-to-reverse version. Choose from three presets — Basic, Medium, or Strong — to balance output size against obfuscation depth. Uses the javascript-obfuscator engine with string array encoding, control flow flattening, and identifier renaming. All processing runs in your browser; your code is never transmitted to a server.

Features

  • Three obfuscation presets

    Basic compacts the code. Medium adds Base64-encoded string arrays. Strong applies RC4 string encryption and control flow flattening for maximum protection.

  • String array encoding

    Extracts all string literals into an encrypted array referenced by index. Reverse-engineering requires reconstructing the lookup table before any strings are readable.

  • Control flow flattening

    Restructures if/else and switch blocks into a state-machine loop, hiding the original execution order. Available in the Strong preset.

  • Size impact indicator

    Shows the byte overhead added by obfuscation so you can choose a preset that fits your payload budget.

How to obfuscate JavaScript online

Protect your JS source code from casual inspection in three steps.

  1. Paste your JavaScriptDrop your source code into the left panel. Valid ES5 or ES6+ code is accepted.
  2. Choose a presetSelect Basic for minimal overhead, Medium for string array encoding, or Strong for maximum obfuscation (produces larger output and is slower to process).
  3. Click ObfuscateThe obfuscated output appears in the right panel. Byte counts and the size overhead percentage are shown in the toolbar.
  4. Copy and deployCopy the output and replace your original script. The obfuscated version runs identically in all browsers.

Examples

Obfuscate a configuration object

Input
const apiConfig = {
  endpoint: "https://api.example.com/v2",
  timeout: 5000,
  retries: 3
};
Output
const _0x3f2a=['https://api.example.com/v2'];(function(_0x1b,_0x4c){...}(_0x3f2a,0x1a3));const apiConfig={'endpoint':_0x5e('0x0'),'timeout':0x1388,'retries':0x3};

In Medium preset, string literals move into an encoded array. Numeric values are converted to hex. The original structure is preserved but hard to read at a glance.

Frequently Asked Questions

What is JavaScript obfuscation?
Obfuscation transforms source code into a version that behaves identically but is much harder for humans to read and reverse-engineer. It renames variables to meaningless identifiers, encrypts string literals, and optionally restructures control flow to obscure program logic.
Does obfuscation make my code impossible to reverse-engineer?
No. Obfuscation is a deterrent, not encryption. A determined engineer with enough time can deobfuscate any JavaScript that runs in a browser, because the browser must ultimately execute it. It raises the cost and effort of casual copying but is not a security boundary.
What is the difference between the three presets?
Basic: compact output with no encryption — fast, minimal overhead. Medium: adds a Base64-encoded string array that hides all string literals — moderate overhead (~20–50%). Strong: adds RC4 string encryption and control flow flattening — maximum protection but significantly larger output and slower execution.
Will obfuscated code run slower?
Basic and Medium have negligible performance impact. Strong obfuscation with control flow flattening can noticeably slow down hot code paths because the state-machine loop adds overhead per iteration. Avoid using Strong on performance-critical code like game loops or real-time data processing.
Can I obfuscate TypeScript or JSX?
The obfuscator works on plain JavaScript. Compile TypeScript or JSX to JS first, then obfuscate the output. Obfuscating before compilation will produce errors.
Is obfuscation the same as minification?
No. Minification reduces file size by removing whitespace and shortening identifiers. Obfuscation prioritizes making code hard to understand, which often increases file size. You can apply both: minify first, then obfuscate — or just minify if your goal is performance rather than IP protection.