CreepJS alternative: the same kind of lie detection, explained

CreepJS is an open-source research project that shows how far browser fingerprinting can go and how anti-fingerprinting tools give themselves away. It is deep and very technical. SpoofLens builds on a similar idea for a wider audience: it gives a verdict, explains each finding in plain words and adds checks that need a server.

	CreepJS	SpoofLens
What it is	Open-source research project (MIT license)	Free online service
Main audience	Researchers and developers	Developers, QA, website owners, everyday users
Detects tampered JavaScript	Yes, in depth	Yes: replaced built-in functions, Web Worker and iframe mismatches
Source code	Open	The signal collector will be published as open source
Price	Free	Free; Pro and Business plans are coming

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What CreepJS is

CreepJS is a project by Abraham Juliot, published on GitHub under the MIT license, with the official demo on GitHub Pages. Its stated goal is research and education: it tests how well fingerprinting holds up against anti-fingerprinting tools and exposes weak spots in browsers and privacy extensions. It detects JavaScript tampering, including so-called prototype lies, and recognises the patterns that extensions and spoofing tools leave behind.

Its output is aimed at people who already know what an AudioContext or an OffscreenCanvas is, which is ideal for research. The project also warns that copies on other domains are unofficial and may collect your data, so use the official address if you want to try it.

What SpoofLens adds

SpoofLens uses the same core idea, that spoofing shows up as contradictions, and turns it into a verdict anyone can read. Each finding says what was found, why it matters and what innocent causes it might have.

It also checks what only a server can see: the network your IP belongs to (home provider, data center or VPN), whether it is a Tor exit node, proxy headers, and whether the User-Agent, Client Hints and languages your browser sent in its HTTP headers match what JavaScript reports. Comparing the two sides is one of the strongest ways to spot a forged browser.

When CreepJS is the better choice

You research fingerprinting or test a privacy extension in depth.
You want to see many APIs and their quirks at once.
You are comfortable reading technical output.

When SpoofLens fits better

You need a clear answer: does this browser look consistent?
You want JavaScript data compared with server-side data.
You need to explain the result to someone non-technical.
You run a website and want this kind of check for your visitors. An API and plugins are in preparation.

Frequently asked questions

Is SpoofLens based on CreepJS code?: No. SpoofLens is written from scratch. It shares the general approach of looking for contradictions, which is common in fingerprinting research.
Does SpoofLens store my fingerprint?: No. The signals are sent to our server once for the cross-check and are not saved. Only the daily number of checks is counted.
Is SpoofLens affiliated with CreepJS?: No. CreepJS is an independent project. This comparison is based on its public repository and description.