Since it is no longer sold or officially hosted by Microsoft, your options for obtaining it include:
The developer searches for FrontPage 2003 portable to make quick edits without installing. Finds a link in a forum, but realizes it's from an unknown source. They hesitate, consult a colleague, and learn that using such software is a security risk. They suggest alternatives like HTML editing with modern tools or using a local web server with older software via a virtual machine. The client agrees to explore modernization with security in mind. microsoft frontpage 2003 portable download link
The "Web 1.0" aesthetic is a specific design choice for some retro-enthusiasts today. Modern Alternatives to FrontPage Since it is no longer sold or officially
Microsoft released Expression Web 4 for free before discontinuing it. It is the direct successor to FrontPage and can open FrontPage themes, shared borders, and navigation structures. It is far more stable on modern Windows. They suggest alternatives like HTML editing with modern
Microsoft FrontPage 2003 is a web authoring tool. Because Microsoft ended support in 2014, there is no official "portable" version or direct download link from Microsoft's primary website. Use extreme caution when seeking "portable" versions from third-party sites, as these are often unofficial and may contain security risks. Where to Find FrontPage 2003