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Custom Branded Subdomain Setup

This guide explains how to configure SpeedSize to use a custom branded subdomain (for example, media.website.com) instead of the default SpeedSize CDN domain. Using a custom subdomain results in cleaner, brand-consistent media URLs and is commonly required for advanced setups.

What Is a Custom Branded Subdomain?

By default, SpeedSize delivers media through its CDN domains (for example, aicdn.speedsize.com) and includes your Client ID in the URL.

With a custom branded subdomain:

  • Your own domain is used as the media prefix
  • Media URLs look cleaner and fully brand-aligned
  • Depending on the setup, the Client ID may be omitted from the URL

Example

Default setup:

https://aicdn.speedsize.com/CLIENT_ID/website.com/images/image.jpg

Custom branded subdomain:

https://media.website.com/CLIENT_ID/website.com/images/image.jpg

Custom branded subdomain without Client ID (uses a dedicated CDN distribution):

https://media.website.com/website.com/images/image.jpg

How to Set Up a Custom Branded Subdomain

Custom subdomain setup is usually discussed and configured during integration if you choose to use it from the start. However, you can also switch to a custom subdomain at any time — the steps are the same in both cases.

  1. Choose Your Subdomain
    Decide which subdomain you want to use for media delivery, for example:
    media.website.com
    cdn.website.com
    images.website.com

  2. Share the Subdomain with SpeedSize team
    Send your chosen subdomain to the SpeedSize team. We will:

    • Configure the CDN on our end

    • Prepare the required DNS records

  3. Add DNS Records
    SpeedSize will provide DNS instructions (typically CNAME records). Add these records to your DNS zone for the selected subdomain.

  4. Verification and Activation
    Once DNS records are added:

    • Notify the SpeedSize team

    • We will verify the setup and activate the subdomain

  5. Update Media URLs
    After confirmation, update your media URLs to use the custom subdomain as the prefix. For example:
https://media.website.com/CLIENT_ID/website.com/images/image.jpg

Notes

  • Media processing behavior remains the same regardless of URL structure

  • SpeedSize optimization, formats, and delivery logic are unchanged

  • Switching to a custom subdomain does not require changes to SpeedSize transformation parameters

If you have any questions, feel free to contact us at support@speedsize.com.

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