Botd vs Censys

BotD is FingerprintJS's open-source, MIT-licensed JavaScript library that runs entirely in the browser to flag basic automation -- headless Chrome, PhantomJS, Selenium, and similar tools -- without any server round-trip for the detection itself. It ships as an npm package or as a CDN-hosted ES module and returns a plain detected/bot-kind result object from a single detect() call. It is free for any use with no signup; FingerprintJS separately sells a more sophisticated, paid, server-side Bot Detection API for teams that need those extra signals.

Censys grew out of the University of Michigan's ZMap internet-scanning research and now re-scans the full public IPv4 space multiple times a day, fingerprinting open ports, services, and TLS certificates. Its Search API exposes that host and certificate-transparency dataset for asset discovery, exposure monitoring, and threat hunting, and underpins Censys's own attack-surface-management product. Access is account-scoped through an API key, with a limited free community tier and metered paid plans for higher query volume.