There are two primary reasons:
However, browsers and scripts don't need the interface; they just need the code. When you click the "Raw" button on a file, GitHub redirects you to the githubusercontent.com domain to serve you the plain text file without any HTML wrapping.
https://raw.githubusercontent.com/owner/repo/git-ref/path/to/file
https://raw.githubusercontent.com/octocat/Hello-World/master/README.md define githubusercontent
: Accessing files through this domain is subject to GitHub's rate limits. Unauthenticated requests may result in Error 429: Too Many Requests if accessed too frequently from the same IP.
You will most often encounter this domain through its specific subdomains:
You might wonder: Why not just serve raw files on github.com ? There are two primary reasons: However, browsers and
Using curl :
is a domain used by GitHub to serve raw static content .
: Unlike the main site, which renders code with syntax highlighting, these URLs serve the file with the appropriate MIME type (e.g., text/plain or image/png ), allowing browsers and scripts to process them as raw data. Security Considerations What do raw.githubusercontent.com URLs represent? Unauthenticated requests may result in Error 429: Too
: When you drag and drop an image or video into a GitHub issue, pull request, or markdown file, it is automatically uploaded here.
The primary reason GitHub uses this separate domain is for . By serving user-uploaded files from a different domain than the main github.com site, GitHub creates a "sandbox" that helps prevent cross-site scripting (XSS) attacks. This ensures that even if a user uploads a malicious script, it cannot easily access your GitHub session or sensitive cookies on the main platform. Common Subdomains and Their Uses