Deobfuscate JavaScript Online
Free browser tool to deobfuscate and beautify JavaScript instantly
Input
Deobfuscated Output
What Is This Deobfuscate JavaScript Online Tool?
This Deobfuscate JavaScript Online tool reverses common obfuscation patterns and beautifies JavaScript. Paste obfuscated or minified code; get readable output for debugging and analysis. The ECMAScript spec defines the language.
Deobfuscation happens in this tab, so a suspicious script you are picking apart is never uploaded anywhere. Need to go the other direction and obfuscate code? Use JavaScript Obfuscator. For formatting only, use JavaScript Formatter. For validation, use JavaScript Validator.
How to Use This Tool
Paste or Upload
Paste obfuscated or minified JavaScript into the left panel or upload a .js or .txt file. Use Sample to load example code.
View Deobfuscated Output
The right panel shows cleaned and formatted code. Some obfuscation may remain; advanced patterns are hard to fully reverse.
Copy or Download
Copy the readable version out, or Download it as a file to diff against the original. For running code, use JavaScript Console.
Deobfuscate JavaScript Online Examples
Here is an example of deobfuscating JavaScript with mangled variable names.
Example: Obfuscated MSISDN validation
Obfuscated input:
Deobfuscated output:
When to Use Deobfuscate JavaScript Online
When debugging third-party scripts, analyzing malware, or understanding obfuscated code, deobfuscation makes it readable. Great for security review and learning. Tools like Terser and UglifyJS minify; obfuscators add encoding and mangling. For minified (non-obfuscated) code, JavaScript Formatter may be enough. See Chrome DevTools for debugging.
Frequently Asked Questions
Is my data private?
Yes. The unpacking is done by script in this tab, so the code you are inspecting is not uploaded.
Does it work on minified code?
Yes. The formatter can make minified JavaScript easier to read. For minified-only code, JavaScript Formatter may suffice.
Can it fully reverse obfuscation?
It depends on the obfuscation. Simple patterns are reversed. Heavy obfuscation may leave some code hard to read.
Deobfuscator vs Formatter?
Formatter adds indentation. Deobfuscator also reverses encoding, renames variables, and simplifies control flow where possible.
Is it legal to deobfuscate?
Use for debugging your own code, security research, or with permission. Check licenses and terms for third-party code.