Read the spec
Nicely formatted, with updated links.

Original version
The original webpage from fastcgi.com, pulled from the Wayback Machine archive.

Github repository
Repository with markdown version and original HTML page.

Warning

This is not an official website nor is it linked in any way to the original fastcgi.com website and FastCGI copyright owners.

The FastCGI Specification is intellectual property of Open Market, Inc.
Copyright © 1996 Open Market, Inc. 245 First Street, Cambridge, MA 02142 U.S.A.
Tel: 617-621-9500 Fax: 617-621-1703 URL: http://www.openmarket.com/