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Uglify JS

JavaScript minifier and obfuscator. Compress and optimize JS code.

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Demo online
MIT

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What is Uglify JS?

UglifyJS is an open-source JavaScript parsing, minification, compression, and beautification toolkit built for the Node.js runtime environment. Web developers and build tools utilize UglifyJS to convert human-readable JavaScript files into optimized, byte-efficient production scripts. The tool solves the problem of network latency caused by bloated script assets by transforming source code into its smallest syntactically valid equivalent. The primary input to UglifyJS is standard JavaScript source code. Its primary output is a minified JavaScript file along with an optional source map. During processing, UglifyJS strips whitespace, removes line breaks, truncates local variable names, prunes comments, and eliminates unreachable code paths. A source file measuring 120 kilobytes in development can frequently be reduced to under 45 kilobytes after passing through UglifyJS, yielding substantial load-time improvements. First, UglifyJS performs static Abstract Syntax Tree (AST) analysis to inspect and restructure code safely without altering execution logic. Second, it implements scope-aware variable mangling, converting local variable identifiers such as `totalTransactionAmount` into short single-character names like `a` or `b`. Third, it executes dead code elimination, analyzing logic trees to strip out unused function declarations and unreachable `if (false)` code blocks. While rudimentary minification tools rely on basic regular expression text replacement, UglifyJS operates as a true language parser. This structural awareness prevents syntax breakage caused by nested scoping issues or string literal misinterpretations. Compared to modern alternatives like Terser—which originated as a fork of UglifyJS—the original `uglify-js` package remains a widely tested benchmark for ECMAScript 5 code transformation pipelines.

How it works

UglifyJS is an open-source JavaScript parsing, minification, compression, and beautification toolkit built for the Node.js runtime environment. Web developers and build tools utilize UglifyJS to convert human-readable JavaScript files into optimized, byte-efficient production scripts. The tool solve

How to use it

  1. 1Use the UglifyJS tool.
  2. 2Use the UglifyJS tool.
  3. 3Use the UglifyJS tool.
  4. 4Use the UglifyJS tool.

What it can do

  • Compression

Use cases

Assumptions and limitations

Assumptions

  • source: https://github.com/uglifyjs
  • license: Open source
  • privacy: Opens an external demo

Limitations

  • External demo — opens a third-party website that you do not control.
  • License status not stated — verify usage terms before commercial use.
  • Relies on an external source (github.com); availability depends on that service.
  • Focused on the code tools category: JavaScript minifier and obfuscator. Compress and optimize JS code..

Understanding the result

JavaScript minifier and obfuscator. Compress and optimize JS code.

Tool details

  • Clearly flagged when a network request is needed.
  • No account, no sign-up, and no tracking of your content.
  • Powered by uglifyjs (MIT).
Built with
uglifyjs (https://github.com/uglifyjs)
License
MIT
Runs locally
No — requires a network request
Verification
Not yet verified
Input
Code
Output
Compressed File
Open-source source & license

Built with https://github.com/uglifyjs. OpenToolVault provides the discovery and browser interface while crediting the original project maintainers.

Built with
uglifyjs
License
MIT
View source on GitHub

Open-source project

License: MITSource: this projectOfficial site

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References

Frequently asked

What is UglifyJS?

JavaScript minifier and obfuscator. Compress and optimize JS code.

Where can I find the source code?

The source is available at https://github.com/uglifyjs

What license is it?

.

Is it free to use?

Yes, it is open-source and free to use.

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