Express Server-Side Fingerprinting Middleware

express-fingerprint is an Express middleware designed for passive, server-side client fingerprinting. It allows developers to identify incoming requests based on characteristics observable in HTTP request contents without executing any client-side code. The current stable version is `1.2.2`. The library processes information such as the User-Agent string, HTTP Accept headers, and GeoIP data (if available) to generate a unique hash and a detailed component breakdown for each request, accessible via `req.fingerprint`. Releases are infrequent but have recently addressed critical import issues and added TypeScript support. A key differentiator is its strict adherence to server-side data collection, prioritizing privacy by avoiding client-side scripts, and offering extensibility through custom parameter functions to gather additional request-specific data.