quien

Quien is a command-line tool for looking up domain and IP address information. Instead of the plain text output from traditional whois commands, it presents data in an interactive tabbed interface covering domain registration details, DNS records, mail authentication protocols, SSL/TLS certificates, HTTP headers, SEO analysis, and technology stack detection. For IP addresses, it shows network ownership, CIDR ranges, reverse DNS lookups, and ASN data with peering database enrichment. The tool supports both interactive exploration and JSON output for scripting.

Quien is written in Go and developed by retlehs under the MIT license. It uses RDAP as its primary lookup protocol for structured data retrieval, with fallback to traditional WHOIS for domains lacking RDAP support. The SEO tab can optionally integrate with the Chrome UX Report API to display real-user Core Web Vitals metrics when configured with an API key.