IANA RFC8615 defines a “.well-known/” folder for web servers to put metadata fundamental to a web server’s organization, policies or contact information. Some popular files seen under public website https://example.invalid/.well-known/ directory include:

• keybase.txt Verifies ownership of domain for Keybase.io
• security.txt Security incident contact info
• dnt-policy.txt Do Not Track Policy statement
• humans.txt author info