FPScanner review
A focused open-source toolkit for detecting browser automation in your own application.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
FPScanner is an MIT-licensed, open-source JavaScript library for teams that want to detect browser automation on infrastructure they control. It runs client-side in web applications and supports self-hosted deployment. The library collects browser and automation signals, then creates a short-lived browser fingerprint with a JA4-inspired fsid identifier. Its intended audience is developers building bot checks directly into their own applications rather than buyers seeking a managed enforcement platform.
The detection layer covers WebDriver, CDP, Playwright, Selenium and other automation indicators. Cross-context validation compares signals from the main page, iframes and web workers, while timestamp and nonce checks help guard against replay. Teams can optionally encrypt fingerprint payloads with build-time key injection and apply JavaScript code obfuscation. Node.js and Python examples show how to decrypt and validate data server-side, making the package suitable for web stacks that can split collection in the browser from verification in backend code.
FPScanner’s narrow scope is also its main boundary. It focuses on client-side detection and does not provide behavioral detection, custom rules, dashboards or managed mitigation. Operating the npm package, client-side JavaScript and server-side validation remains the team’s responsibility, with documentation and community support as the listed channels. Choose FPScanner when you need open-source building blocks for in-house browser-automation detection and can design the surrounding response workflow. Look elsewhere if you need a hosted service, visual monitoring, behavioral analysis or centrally managed enforcement.
FPScanner pros and cons
- Where it wins
- Detects WebDriver, CDP, Playwright, Selenium and other automation signals
- Cross-context validation spans pages, iframes and web workers
- Fingerprint encryption, obfuscation and anti-replay protections are optional
- Where it doesn't
- Client-side detection does not include behavioral analysis
- No dashboards, rule engines or managed mitigation service
- Teams must deploy and operate the npm package themselves
FPScanner fact sheet, pricing and score →
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