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JS-Confuser

js-confuser.com

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Spec score 8.6 #2 of 34 in Code Obfuscation Software

What it is

JS-Confuser obfuscates JavaScript to make source code harder to understand, copy, reuse, or modify while preserving its functionality. Its browser playground accepts pasted code, lets users choose settings, and produces a downloadable result. The playground runs in the browser, including offline, and says it does not send code or actions to a remote server. Users can start with Low, Medium, or High presets or create custom configurations. Options include renaming variables, concealing strings, flattening control flow, inserting dead code, setting domain or date locks, and tamper protection. The API offers JSConfuser.obfuscate for source code and JSConfuser.obfuscateAST for Babel ASTs; output targets include Browser and Node.js. The editor includes Prettier and a JSON representation of JSConfuser.ts settings. JS-Confuser is described by its maker as free and open source. Obfuscation can increase file size and performance overhead or break a program, and it cannot prevent determined reverse engineers from recovering code or sensitive information. Tamper protection requires eval and non-strict mode.

Spec sheet

What it does
JS-Confuser transforms JavaScript into a less readable representation while aiming to preserve its behavior.Read 15 Oct 2026 · js-confuser.com
Purpose
JS-Confuser obfuscates JavaScript to make code harder to understand, copy, reuse, or modify while preserving its functionality.Read 30 Sep 2026 · js-confuser.com
Integrations
The maker links to an NPM package and GitHub repository; its roadmap lists Webpack and build plugins as planned features.Read 30 Sep 2026 · js-confuser.com
Privacy
The playground runs locally in the browser, including offline, and says code and user actions are not sent to a remote server.Read 15 Oct 2026 · js-confuser.com
Founded
2020Read 28 Sep 2026 · js-confuser.com
Browser playground
The playground lets users paste code, configure options, obfuscate it and download the result.Read 15 Oct 2026 · js-confuser.com
Control-flow obfuscation
Control-flow obfuscation is a listed feature that makes program logic harder to follow.Read 15 Oct 2026 · github.com
Custom extensibility
Custom string encodings accept decoder templates and user-supplied encode and optional decode functions.Read 15 Oct 2026 · js-confuser.com
Documentation depth
Documentation covers getting started, installation, usage, FAQ, options and presets, with individual pages for transformations.Read 15 Oct 2026 · js-confuser.com
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.Read 30 Sep 2026 · js-confuser.com
Function obfuscation
Function obfuscation is included among the project's core features.Read 15 Oct 2026 · github.com
GitHub activity
The public repository shows 525 stars, 68 forks, 25 issues and 706 commits.Read 15 Oct 2026 · github.com
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.Read 15 Oct 2026 · defuscator.com
Installation
The documented installation method is npm install js-confuser.Read 15 Oct 2026 · github.com
Integrity checking
The tool includes an integrity option intended to detect source-code changes.Read 15 Oct 2026 · js-confuser.com
Known tradeoffs
The maker says obfuscation can increase performance overhead and file size, and may break a program in some cases.Read 30 Sep 2026 · js-confuser.com
Licence
The public repository identifies the project as MIT licensed.Read 15 Oct 2026 · github.com
Limit: output size
Reddit commenters report very large percentage increases in output size, including a cited 37,380% increase for a tiny input.Read 15 Oct 2026 · reddit.com
Local processing
The playground runs entirely in the browser, including offline, and says input code and actions are never sent to a remote server.Read 30 Sep 2026 · js-confuser.com
Locks
Domain locks and date-based locks can restrict where or when obfuscated code runs.Read 15 Oct 2026 · github.com
Maker location
The LinkedIn profile associated with Michael Brasington lists Raleigh, North Carolina, United States.Read 15 Oct 2026 · linkedin.com
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.Read 15 Oct 2026 · linkedin.com
Minification
Its minifier performs dead-code removal, constant folding, variable grouping and other shortening transformations.Read 15 Oct 2026 · js-confuser.com
NPM licence and package status
NPM describes the package as a JavaScript obfuscation tool under the MIT License and provides TypeScript declarations.Read 15 Oct 2026 · npmjs.com
NPM release
NPM lists version 2.1.3 as the current package version and reports 12,911 weekly downloads on the page opened.Read 15 Oct 2026 · npmjs.com
Obfuscation options
Options include variable renaming, string concealing, control-flow flattening, dead-code insertion, domain locks, date locks, and tamper protection.Read 30 Sep 2026 · js-confuser.com
Official limitation
The FAQ warns that obfuscation can add runtime overhead, enlarge files and sometimes break programs.Read 15 Oct 2026 · js-confuser.com
Open source
The maker describes JS-Confuser as free and open source.Read 30 Sep 2026 · js-confuser.com
Output targets
The target option supports browser and Node.js execution contexts.Read 15 Oct 2026 · js-confuser.com
Planned integrations
The roadmap lists Webpack and build plugins as planned features rather than current integrations.Read 15 Oct 2026 · js-confuser.com
Praise: accessibility
A Reddit post highlights that the tool is open source and testable directly in a browser.Read 15 Oct 2026 · reddit.com
Presets
Low, Medium and High presets are built in, with documented performance reductions of about 30%, 52% and 98% respectively.Read 15 Oct 2026 · js-confuser.com
Programming API
The API provides JSConfuser.obfuscate for source code and JSConfuser.obfuscateAST for Babel ASTs.Read 30 Sep 2026 · js-confuser.com
Public API
The JavaScript API exposes obfuscate for source strings and obfuscateAST for Babel AST objects, returning a promise for the result.Read 15 Oct 2026 · js-confuser.com
Recent notable change
The 2.1.3 changelog says the release added a way to assert runtime values in response to concerns that control-flow flattening could be defeated by AI-assisted static analysis.Read 15 Oct 2026 · github.com
Security limitation
The FAQ says determined reverse engineers may eventually deobfuscate code and extract secrets or bypass client-side checks.Read 15 Oct 2026 · js-confuser.com
Snyk health
Snyk reports a 78/100 package health score, one maintainer, 25 open issues and no direct vulnerabilities for version 2.1.3.Read 15 Oct 2026 · security.snyk.io
Snyk security
Snyk's database shows no known security issues for the latest package version, while noting dependency vulnerabilities are outside that result.Read 15 Oct 2026 · security.snyk.io
String concealing
String concealing encodes strings so their plain-text values are harder to see.Read 15 Oct 2026 · js-confuser.com
Tamper protection constraints
Tamper Protection requires eval and non-strict mode, may break code, and must be enabled manually due to arbitrary code execution concerns.Read 30 Sep 2026 · js-confuser.com
Tamper-protection constraint
Tamper protection requires eval and non-strict mode, so it can break code or fail in environments that disable eval.Read 15 Oct 2026 · js-confuser.com
Targets
The editor offers Browser and Node.js as output targets.Read 30 Sep 2026 · js-confuser.com
Variable renaming
Variable renaming is one of the repository's listed obfuscation features.Read 15 Oct 2026 · github.com

Plans and prices

Free Free browser playground · npm package/API · low, medium and high presets Read 15 Oct 2026 · js-confuser.com

Every JS-Confuser plan and price →

Strong points and limits

Strong points

  • Free and open source.
  • Browser playground works offline.
  • Low, Medium, High, and custom configurations.
  • API supports source code and Babel ASTs.
  • Browser and Node.js output targets.

Limits

  • Obfuscation may increase file size and overhead.
  • Obfuscation can break programs.
  • Determined reverse engineers may recover code.
  • Tamper protection requires eval and non-strict mode.

Who it suits

JS-Confuser suits developers who want to obfuscate JavaScript in a browser playground or through an API, with Browser or Node.js output. Its offline browser workflow may suit users who want code to remain on their device.

JS-Confuser in depth

Read the full write-up

JS-Confuser is a free, open-source JavaScript obfuscator for developers who want to make code harder to inspect or reuse. It suits projects that need configurable browser or API workflows; its transformations raise the effort of analysis, but they cannot guarantee that code or secrets stay hidden.

Overview

JS-Confuser reshapes JavaScript to make copying, modification, and understanding more difficult while aiming to preserve its behavior. The browser playground processes code locally, even offline, and says it does not send input or actions to a remote server. That makes it a sensible option for trying obfuscation without uploading source; the API is the better fit for a programmatic workflow.

Obfuscation is a deterrent, not a security boundary. A determined reverse engineer may still deobfuscate the output or extract sensitive information, so JS-Confuser is not a substitute for keeping secrets out of distributed code. Transformations can also increase file size and runtime overhead, and may break a program.

Key features

Low, Medium, and High presets offer starting points, while custom configurations let developers tune the result. Options include variable renaming, string concealing, control-flow flattening, dead-code insertion, domain and date locks, and tamper protection. This breadth is useful when identifier renaming alone is not enough, but adding stronger transformations can compound size, performance, and compatibility costs.

The playground accepts pasted JavaScript, applies configured options, and lets users download the result. Browser and Node.js are the available output targets. Prettier is included, and JSConfuser.ts can be edited as a JSON representation of obfuscator settings, including custom implementations.

For integration into code, the API exposes JSConfuser.obfuscate for source and JSConfuser.obfuscateAST for Babel ASTs. The maker links an NPM package and GitHub repository; Webpack and build plugins appear on the roadmap as planned features, so teams seeking those integrations should not assume they are already part of the workflow.

Tamper protection is the sharpest compatibility caveat: it requires eval and non-strict mode, can break code, and must be enabled manually because it can execute arbitrary code. It is a poor default for projects that depend on strict mode or cannot accept that execution constraint.

Pricing

The Free plan costs free and is open source. It includes the obfuscator without a paid tier barrier, making it a practical fit for individual developers and projects that can absorb the runtime and compatibility tradeoffs. The plan is described as free and open source; there is no paid plan to compare against.

Platforms

JS-Confuser supports JavaScript, Node.js, and browser targets, with API, Linux, macOS, web, and Windows platforms. Its deployment model is hybrid, and API is the build integration. The browser playground's local processing is particularly useful when source should remain on the user's machine, while the API better suits repeatable use in a development workflow.

Who it's for

This is a good fit for JavaScript developers who want a no-cost way to make shipped code less straightforward to copy or analyze, whether they prefer a browser playground or an API. It is less suitable when runtime overhead, file size, strict-mode compatibility, or reliable secrecy is paramount. Teams needing established Webpack or build-plugin support should consider whether the current API workflow is sufficient.

Pros and cons

Pros: Free and open source, with a browser playground that works offline and keeps input local.

Pros: Multiple transformation options, presets, custom settings, and API methods for source code and Babel ASTs support different levels of control.

Cons: Increased file size, performance overhead, and possible breakage make stronger obfuscation a tradeoff rather than a free improvement.

Cons: Tamper protection's eval and non-strict-mode requirements limit where it can be used safely.

Cons: Obfuscation cannot prevent determined reverse engineering or safely conceal sensitive information.

Alternatives

For a broader shortlist, see Code Obfuscation Software.

Tigress is an alternative for readers comparing another obfuscation tool.

ByteHide Shield may suit readers who want a freemium option with a free core-obfuscation plan and paid advanced techniques.

ProGuard is a free, open-source option for Java and Kotlin shrinking rather than JavaScript obfuscation.

Allatori is another freemium alternative; its single-developer license update is $75 a year for 12 months of support, updates, and upgrades.

DashO may be worth comparing if a free trial and team or enterprise plans are more relevant than a free plan.

Redgate SQL Provision is for readers evaluating SQL data provisioning and masking, not JavaScript obfuscation.

Enigma Protector is a paid alternative with a free trial; its Online Activation Panel — Light costs $24 a month, with an initial payment covering at least six months.

Obfuscar is a free, MIT-licensed option for basic.NET assembly obfuscation.

Verdict

Choose JS-Confuser if you want a free, open-source JavaScript obfuscator with both local browser use and an API, and can treat the output as a barrier rather than protection against determined analysis. Look elsewhere if you need dependable secrecy, cannot tolerate compatibility or performance costs, or require tamper protection in strict-mode code.

Verdict

JS-Confuser offers multiple obfuscation controls and browser or API workflows without a listed price. Treat obfuscation as a barrier rather than a guarantee, and note the compatibility constraints of tamper protection.

Where Specifiction places it

Alternatives to JS-ConfuserAll alternatives →