Unknown file extension
File type: Unknown file
The .cdn-cgi file extension does not identify a known public file format or a standard application file.
It is commonly seen as part of a Cloudflare /cdn-cgi/ URL path rather than as the name of a documented file type.
File type category:
Unknown file
Date updated: October 4, 2026
Cloudflare uses the /cdn-cgi/ path for server-generated services and resources on websites protected or delivered by its network. These responses can support functions such as security checks and other Cloudflare features, but they do not constitute a single downloadable file format called CDN-CGI.
The content of a file ending in .cdn-cgi therefore depends on the website and the operation that produced or downloaded it. There is no established structure, associated application, or standalone format that can be identified from this extension alone.
There is no dedicated program for opening a .cdn-cgi file. If it contains readable text or web content, a text editor or web browser may display it; otherwise, its content must be identified from the source that created or downloaded it.
A .cdn-cgi file cannot be converted reliably because the extension does not define a specific format. Conversion is possible only after the underlying content has been identified, using a tool appropriate for that content.
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