Validator.w3.org - W3C's easy-to-use markup validation service, based on SGML and XML parsers. stats and earnings.
HTTP/1.1 200 OKdate: Fri, 23 Oct 2020 06:57:32 GMTserver: Apache/2.4.38 (Debian)cache-control: max-age=604800expires: Fri, 30 Oct 2020 06:57:32 GMTvary: Accept-Encodingcontent-encoding: gzipcontent-length: 5080content-type: text/html; charset=utf-8accept-ranges: bytes