CDN and asset URL strategy
How SGEN delivers your assets, why URL stability matters, and how to keep cache behaviour working for you — not against you.
A slow image is a broken experience.
A broken asset URL after a migration or rename is a broken page.
An asset that keeps re-downloading instead of serving from cache is wasted bandwidth and slower load times for every visitor who should have had the cached version.
SGEN routes all site assets — images, CSS, JavaScript, uploaded media files — through its platform CDN.
The CDN is always on.
You do not activate it separately.
You do not choose a CDN provider.
The platform handles the delivery layer.
What you do control is the shape of your asset URLs, the media files you upload and how you name them, and the cache headers that govern how long edge nodes and browsers hold a cached version.
Getting these right means faster page loads, stable links in external references, and predictable cache invalidation when you update a file.
This page covers how the SGEN CDN works, how asset URLs are structured, what URL patterns to avoid, and how to handle cache invalidation when you update a critical asset.
What is this for?
Use this page when you want to understand how your site's assets are delivered, or when you are troubleshooting an asset that is loading slowly, returning a stale version, or producing broken URLs after a change.
This page is a how-to and reference combined.
It does not cover custom CDN configurations or third-party CDN integration — SGEN does not currently support routing through a separately-contracted CDN.
It does not cover server-side caching for dynamic pages — that is a platform-managed layer outside operator configuration.
Good use cases
- You are launching a site and want to understand the asset URL format before you hard-code any image references in external marketing materials or email campaigns.
- You updated a logo or hero image and visitors are still seeing the old version — you want to know whether this is a CDN cache issue and how to clear it.
- You are auditing a migrated site and find old asset URLs (from the previous platform) in page content.
- You are uploading a large batch of media and want to name files correctly to avoid future URL hygiene problems.
- You are building a landing page in an external tool that pulls images from your SGEN media library and you need to know the stable URL pattern.
What NOT to use this for
- Serving self-hosted video files through the CDN at scale.
- Bypassing CDN delivery to serve assets from a custom origin.
- Using CDN URLs as permanent hard-coded references in external systems without reading the URL stability section first.
How this connects to other features
- Subdomain and DNS — the CDN serves assets under your custom domain once DNS is verified.
- Optimise for SEO — image alt text, file naming, and page-speed scores all connect to asset strategy.
- Security — the CDN enforces HTTPS for all asset delivery.
- Backup and restore — media assets are captured in backups.
Before you start
- Review the file naming conventions in this page before uploading a large batch.
- If you are auditing broken asset references on a migrated site, check both page content and any custom code blocks for hard-coded old-platform URLs.
- If you are about to update a hero image or logo that appears on many pages, read the cache invalidation section before uploading.
Where to find it
Media assets are managed in the admin → Media.
File upload, file rename, and the media catalog live there.
Asset URL information for a specific file is available in the media file's detail panel — click any file in the Media library to see its CDN URL, file size, dimensions, and upload date.
Cache management tools are in the admin → Settings → Performance.
How the SGEN CDN works
SGEN's CDN sits between the visitor's browser and the origin server.
When a visitor requests an asset (an image, a CSS file, a JavaScript bundle), the request hits the nearest CDN edge node.
If the edge node has a cached copy of the asset, it serves the cached copy directly.
If not, it fetches from the SGEN origin, caches the result, and serves it.
Edge nodes are geographically distributed.
A visitor in Singapore hits a Singapore-region edge node; a visitor in Germany hits a European edge node.
The result is that assets load from a node close to the visitor rather than from a single origin server.
Assets have cache lifetimes set by the platform.
Static assets (CSS, JavaScript bundles, fonts) carry long cache lifetimes — often 30 days or more — because they do not change between deploys.
Media files (images, uploaded PDFs) carry shorter lifetimes because operators update them more frequently.
The exact cache lifetime for each asset type is managed by the platform and is not operator-configurable on a per-file basis.
Steps
1. Understand the asset URL structure
Every file uploaded to SGEN Media gets a CDN URL in this form:
https://[your-domain]/sgen-media/[year]/[month]/[filename]Before your custom domain is connected, the CDN URL uses the SGEN-hosted domain:
https://[site-id].sgen.com/sgen-media/[year]/[month]/[filename]After your custom domain is connected and verified, new uploads produce URLs under your custom domain.
Existing files uploaded before domain connection retain the SGEN-hosted URL unless you re-upload them.
The path structure sgen-media/[year]/[month]/[filename] reflects the upload date.
An image uploaded in May 2026 lives at .../sgen-media/2026/05/filename.jpg.
An image uploaded in June 2026 lives at .../sgen-media/2026/06/filename.jpg.
This path is permanent for the life of the file.
If you re-upload the same filename in a different month, the new upload gets a new path.
The old URL still resolves to the old file until the old file is deleted.
2. Apply file naming conventions
File names become part of the permanent CDN URL.
A file named IMG_2847.jpg produces a URL with IMG_2847.jpg in it — unhelpful for SEO, unhelpful for human readability in external references.
Apply these conventions before uploading:
Use lowercase letters, numbers, and hyphens only.
No spaces (converted to %20 in URLs, which breaks some tools).
No underscores (treated as spaces by some search engine crawlers).
No special characters.
Name by content, not by camera roll.hero-banner-spring-collection.jpg is a stable, meaningful name.IMG_2847.jpg is not.
Include a descriptor and context.team-photo-founders.jpg is more searchable and referenceable than team.jpg.
Keep names under 60 characters.
Long filenames produce long URLs.
Long URLs truncate in email clients, SMS, and some social platforms.
Version in the name if needed — not by re-uploading the same filename.
If a logo updates, upload logo-v2.jpg rather than overwriting logo.jpg.
Overwriting does not immediately clear CDN caches; versioning by name does.
3. Upload optimised files
The CDN serves whatever you upload.
It does not resize, reformat, or compress images automatically unless the site has the image optimisation module active.
Uploading a 6 MB uncompressed PNG and expecting the CDN to make it fast is the wrong operating assumption.
Before uploading:
- Resize to the display size. A hero image at 1920 × 1080 px is appropriate for a full-width banner.
- Compress before uploading. Tools like Squoosh (free, web-based) reduce file size by 50-80% with minimal visible quality loss.
- Use the right format. JPEG for photographs.
- Toggle WebP conversion and compression ON in the admin → Media before uploading a batch.
4. Manage cache invalidation
When you update an asset, the CDN may serve the old version to visitors whose edge node has a cached copy.
The cache has a lifetime; after it expires, the edge node fetches the updated file.
For most updates this is acceptable.
For critical updates (a corrected price on a product image, a fixed legal notice, a broken logo), waiting for natural cache expiry is not.
To invalidate a specific file's cache immediately:
Open the admin → Media, find the file, and open its detail panel.
Click Invalidate CDN cache.
The platform sends a purge request to all edge nodes for that specific URL.
The invalidation takes effect within one to two minutes globally.
After invalidation, the next request for the file from any edge node fetches fresh from the origin and caches the new version.
If you uploaded a new file with a different name (versioning by name — the recommended pattern), no cache invalidation is needed.
The new URL is not yet in any CDN cache; the first request from any edge node fetches from origin.
For a large batch of assets that all need cache clearing at once, use the admin → Settings → Performance → Clear CDN cache.
This purges all cached assets for the site across all edge nodes.
Use this sparingly — a full cache clear means all assets refetch from origin on the next request, which increases origin load and temporarily slows asset delivery until edge nodes repopulate.
5. Audit and fix broken asset references
After a migration or a large media reorganisation, some page content may contain hard-coded asset URLs that no longer resolve.
To find broken asset references:
Open the admin → Settings → Performance → Asset audit.
The asset audit scans all pages and posts for image and media references that return a non-200 response from the CDN.
The audit takes a few minutes on a large site.
The report lists every broken reference with the page or post it appears on and the URL that is failing.
Open each page listed in the report.
Locate the broken reference in the content editor.
Replace the old URL with the correct CDN URL from the Media library (copy from the file's detail panel).
For broken references in custom code blocks, open the admin → Custom Codes.
Search for the old URL pattern in the code list.
Update the URL in the code block.
For references embedded in template-level HTML (header, footer), open the admin → Appearance → Header or Footer and update the URL there.
What success looks like
The CDN is working correctly when:
- Page load time for image-heavy pages is consistently under 3 seconds on a standard connection.
- Asset URLs in your content match the expected
sgen-media/[year]/[month]/[filename]pattern under your custom domain. - The asset audit in Performance shows zero broken references.
- After a cache invalidation, the updated file version is visible in the browser within two minutes on a hard refresh.
- Media file names in the library follow the lowercase-hyphenated convention and are descriptive.
What to do if it does not work
- Old image still showing after uploading a replacement.
- Asset URL broken after renaming a file.
- Images loading slowly even though they are served from the CDN.
- Full CDN cache clear did not speed up the site.
- Asset audit shows a broken reference but the page looks fine.
- Mixed-content warning in the browser console.
Examples
Example A — pre-launch asset naming audit.
Before launching a site migrated from a previous platform, an operator opens Media and reviews every file in the library.
Files named Photo1.jpg, final_v3.png, and IMG_9847.JPG are renamed to about-team-2026.jpg, service-illustration-branding.png, and client-headshot-ada-reyes.jpg.
Each rename produces a new CDN URL.
The operator runs the asset audit after renaming to confirm no page references are broken.
Three broken references appear — pages still referencing the old filenames.
All three are updated in the content editor.
The audit re-runs clean.
Launch proceeds.
Example B — logo update requiring immediate cache clear.
A brand redesign ships on a Tuesday.
The new logo is uploaded as logo-primary-2026.svg.
The old logo is still referenced by the old filename in the header template.
The operator updates the header template reference to the new filename.
They also invalidate the CDN cache for the old logo file.
Within two minutes, every visitor refreshing the site sees the new logo.
No 24-hour wait for natural cache expiry.
Example C — finding and fixing post-migration broken images.
A content-heavy blog migrates from another platform.
The old platform used a different media URL pattern.
After migration, 40% of post images are broken.
The operator runs the asset audit.
The report lists 83 broken image references across 61 posts.
They use Find and Replace in the content editor to swap the old platform's base URL with the SGEN CDN base URL for all image references in one pass.
The audit re-runs: 2 remaining broken references in custom code blocks.
Those are fixed manually.
Second audit: clean.
Reference — CDN asset type cache lifetimes
| Asset type | Default cache lifetime | Can operator adjust? |
|---|---|---|
| Uploaded images (JPEG, PNG, WebP) | 7 days | No — per-file invalidation available |
| Uploaded SVG | 7 days | No — per-file invalidation available |
| Uploaded PDF and documents | 24 hours | No — per-file invalidation available |
| CSS bundles (platform-managed) | 30 days | No |
| JavaScript bundles (platform-managed) | 30 days | No |
| Custom code block inline assets | Follows page cache | No |
Common questions
Does the CDN affect my site's Google PageSpeed score?
Yes.
Assets served from a CDN with edge nodes close to the evaluating server score better on time-to-first-byte for those assets.
The primary driver of PageSpeed score for asset delivery is file size — the CDN delivers efficiently, but it cannot make a 4 MB image load fast.
Compress before uploading.
Can I use SGEN CDN URLs in external newsletters or social posts?
Yes, with the caution that CDN URLs include the year-and-month path segment from upload date.
A URL you embed in a newsletter sent in May 2026 will still work in 2027 as long as the file has not been deleted.
Do not delete files that are referenced in published, unchangeable content (sent emails, social posts).
Can I connect Cloudflare in front of SGEN's CDN?
Cloudflare can be used as the DNS layer (Cloudflare's DNS proxy / CDN in front of SGEN) but this creates a double-CDN setup that complicates cache management.
The recommended approach is to use Cloudflare DNS-only mode (grey cloud, not orange cloud) so Cloudflare handles DNS but not CDN proxying.
Ask support before enabling Cloudflare's orange-cloud proxy mode on a SGEN site.
What happens to asset URLs when I transfer a site between accounts?
Asset URLs contain the site's CDN path, not the account path.
A site transfer preserves asset URLs; they continue to resolve after the transfer.
Custom domain URLs continue to work as long as DNS still points to SGEN.