Profundis

Profundis is built for people who investigate websites and the servers behind them, such as security researchers and teams mapping what an organization exposes online. You start with a domain, an IP address or a technology string like nginx, and it searches indexed hosts, DNS records, TLS certificates and WHOIS records. Pivot turns one result into a graph, so you can see which other domains share an address, a certificate, a favicon, a tracking identifier or a registrant, then pivot again from any of them. Saved queries can run as monitors that send new matches by email or to a team's tools, and the same searches are available over an API and an MCP server for AI assistants. The free plan gives 25 credits a month and 300 subdomains per enumeration. Solo costs $45 a month for 2,500 credits with API and WHOIS access, and a 7-day pass is $18. Profundis is run by Perspective Analytics SAS in France, and its own docs say a shared host or icon is a lead, not proof that two sites have the same owner.