Serving GitHub Files via CDN with jsDelivr (Short and Clear Guide)

If you want to serve a single file in a public GitHub repo quickly, securely and without cache problems, there is no need for extra infrastructure for most scenarios. jsDelivr allows you to use GitHub directly as a CDN source.

This article focuses on “how to use it correctly” rather than “why”.

Basic URL format

https://cdn.jsdelivr.net/gh/<user>/<repo>@<version>/<path>

• <user>: GitHub username
• <repo>: repository name
• <version>: commit SHA, tag or branch
• <path>: file path in repo

Critical point: use commit SHA as version. Using Branch or main produces a cache surprise.

Real example (file in this blog)

Source file (GitHub):

https://github.com/fmarslan/fmarslan.github.io/blob/a3d76ec02081dfc283f20980ef41797978141d7b/assets/js/post-enhancements.js

jsDelivr CDN URL:

https://cdn.jsdelivr.net/gh/fmarslan/fmarslan.github.io@a3d76ec02081dfc283f20980ef41797978141d7b/assets/js/post-enhancements.js

Usage in HTML:

<script src="https://cdn.jsdelivr.net/gh/fmarslan/fmarslan.github.io@a3d76ec02081dfc283f20980ef41797978141d7b/assets/js/post-enhancements.js"></script>

This URL:

• Immutable
• CDN cache works safely
• When the file changes, it means new commit = new URL

CLI and runtime examples

curls

curl -L \
"https://cdn.jsdelivr.net/gh/fmarslan/fmarslan.github.io@a3d76ec02081dfc283f20980ef41797978141d7b/assets/js/post-enhancements.js"

Node.js

import fetch from 'node-fetch';

const url =
  'https://cdn.jsdelivr.net/gh/fmarslan/fmarslan.github.io@a3d76ec02081dfc283f20980ef41797978141d7b/assets/js/post-enhancements.js';

const res = await fetch(url);
if (!res.ok) throw new Error(res.statusText);

const content = await res.text();
console.log(content);

Good practices (important for prod)

• Use Commit SHA → There is no cache invalidation problem.
• If the file has been updated → new commit, new URL.
• jsDelivr offers public repo only.
• If authentication, confidential data, PII → this method is wrong.
• For critical prod loads → Consider your own edge solution like S3 + CloudFront / Cloudflare.

Common problems

I’m getting a 404

• Repo name, path or commit SHA is incorrect.
• Check if the file actually exists in that commit.

File sounds old

• You are using Branch.
• Switch to Commit SHA.

Access is slow on corporate network

• jsDelivr rate-limit or network policy. *Alternative CDN may be required.

When does it make sense and when does it not?

Makes sense

• Blog, documentation, static JS/CSS
• Small helper scripts
• Immutable assets

Unreasonable

• Secret code
• Frequently changing runtime dependencies
• Critical prod components requiring SLA

In summary: If you want public, small and the URL should change when it changes, jsDelivr is sufficient. The problem here is not technical; using branch URL in wrong place.

If you want, in the next step, we can put the S3 + CloudFront or Cloudflare Workers equivalents of the same file side by side and clarify the differences.