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JS-Confuser
What it is
JS-Confuser is a free, open-source JavaScript obfuscator that makes code harder to understand, copy, reuse, or modify while seeking to preserve functionality. Its browser playground lets users paste code, select settings, and download an obfuscated result; processing takes place in the browser, including offline, and the tool says code and actions are not sent to a remote server. Users can choose Low, Medium, or High presets or configure options such as variable renaming, string concealing, control-flow flattening, dead-code insertion, domain and date locks, and tamper protection. The API provides JSConfuser.obfuscate for source code and JSConfuser.obfuscateAST for Babel ASTs. Output targets include Browser and Node.js. The editor includes Prettier and lets users edit a JSON representation of JSConfuser.ts settings, including custom implementations. Obfuscation can increase file size and performance overhead or break a program; it cannot prevent determined reverse engineers from recovering code or sensitive information. Tamper protection requires eval and non-strict mode, may break code, and must be enabled manually.
For and against
For
- Free and open source
- Browser playground works offline
- Input code and actions are not sent remotely
- Offers three presets and custom configurations
- API supports source code and Babel ASTs
Against
- Obfuscation can increase file size and performance overhead
- Obfuscation may break a program
- Determined reverse engineers may recover code or sensitive information
- Tamper protection requires eval and non-strict mode
The verdict
JS-Confuser offers configurable obfuscation through a browser playground and programming API. Its maker notes that obfuscation can cause breakage and does not guarantee protection from determined reverse engineers.
Who it suits
It suits JavaScript developers who want to obfuscate code in a browser playground or through an API. Users should weigh the possible performance, size, and compatibility costs against the limits of obfuscation.
Plans and prices
Free
browser playground · npm package/API · low, medium and high presets
Read 15 Oct 2026 · js-confuser.com
On the record
- Browser playground
- The playground lets users paste code, configure options, obfuscate it and download the result.js-confuser.com · read 15 Oct 2026
- Control-flow obfuscation
- Control-flow obfuscation is a listed feature that makes program logic harder to follow.github.com · read 15 Oct 2026
- Custom extensibility
- Custom string encodings accept decoder templates and user-supplied encode and optional decode functions.js-confuser.com · read 15 Oct 2026
- Documentation depth
- Documentation covers getting started, installation, usage, FAQ, options and presets, with individual pages for transformations.js-confuser.com · read 15 Oct 2026
- Formatting and configuration
- The playground includes Prettier and lets users edit JSConfuser.ts as a JSON representation of obfuscator settings that can also include custom implementations.js-confuser.com · read 30 Sep 2026
- Function obfuscation
- Function obfuscation is included among the project's core features.github.com · read 15 Oct 2026
- GitHub activity
- The public repository shows 525 stars, 68 forks, 25 issues and 706 commits.github.com · read 15 Oct 2026
- Independent deobfuscation result
- Defuscator's September 2026 test recovered strings from a JS-Confuser 2.1.3 low-preset sample, while the high preset remained virtualized in a bytecode VM.defuscator.com · read 15 Oct 2026
- Installation
- The documented installation method is npm install js-confuser.github.com · read 15 Oct 2026
- Integrations
- The maker links to an NPM package and GitHub repository; its roadmap lists Webpack and build plugins as planned features.js-confuser.com · read 30 Sep 2026
- Integrity checking
- The tool includes an integrity option intended to detect source-code changes.js-confuser.com · read 15 Oct 2026
- Known tradeoffs
- The maker says obfuscation can increase performance overhead and file size, and may break a program in some cases.js-confuser.com · read 30 Sep 2026
- Licence
- The public repository identifies the project as MIT licensed.github.com · read 15 Oct 2026
- Limit: output size
- Reddit commenters report very large percentage increases in output size, including a cited 37,380% increase for a tiny input.reddit.com · read 15 Oct 2026
- Local processing
- The playground runs entirely in the browser, including offline, and says input code and actions are never sent to a remote server.js-confuser.com · read 30 Sep 2026
- Locks
- Domain locks and date-based locks can restrict where or when obfuscated code runs.github.com · read 15 Oct 2026
- Maker location
- The LinkedIn profile associated with Michael Brasington lists Raleigh, North Carolina, United States.linkedin.com · read 15 Oct 2026
- Maker project date
- Michael Brasington's LinkedIn project entry dates JS-Confuser to May 2021 and describes it as a TypeScript tool published on NPM.linkedin.com · read 15 Oct 2026
