Media Proxy (Alpha)

By default, you would upload and store all files in your Uploadcare projects. Sometimes all files are already uploaded on the web, so there's an extra step to get them into your Uploadcare storage.

Media Proxy allows you skip this step so you can deliver your files via Uploadcare CDN instantly. This way, you can integrate Uploadcare into your solution with only minor image src modifications and without moving any files. The older links will still work. Also, you can use Image Transformations and other features over this delivery mehtod.

By the way, Adaptive Delivery feature has Media Proxy under the hood. If you want to have an automatic workflow with minimal configuration, try Adaptive Delivery first. Continue to Media Proxy for a more manual approach.

Setting Up

Step 1. Get a Proxy Endpoint

Note: The feature is still in alpha, and therefore, it's not added to the Dashboard yet.

To start using Media Proxy, please contact our support and we'll process your request individually.

We'll generate a Proxy Endpoint (e.g., for a specific Uploadcare project. Also, you can add a custom CNAME to have a subdomain like This Endpoint will be a part of URL for all files you want to deliver with Media Proxy.

Step 2. Provide a List of Allowed Domains

Also, we'll ask you to provide domain names you’d want the proxy to fetch files from. It can be your website or another domain with your media files.

Using Media Proxy

Here's how to use Media Proxy after it's set up.

Step 1. Check How It Works

Add the Media Proxy prefix that contains your Endpoint to a file URL on the allowed domain. For example: + =

After that, image.jpg will be delivered via Uploadcare CDN. The original file will remain at its original place, so that older references will work as well.

Step 2. Apply Image Transformations

You can apply transformations to images by adding one of the respective URL Directives between the prefix and media URL.

This CDN operation will resize image.jpg to 500 px in width by adding -/preview/-/resize/500x/:

As a result, image.jpg will be resized and delivered with Uploadcare CDN.

Step 3. Add Proxy Prefixes to Your Media

Now you can add prefixes to all images using your IDE or text editing tool. Apply CDN operations when needed.

You can also optimize your responsive image handling workflow and free up some storage space by deleting image versions in different sizes for adaptive layouts.

Uploadcare resizes images on the fly and you don't have to save all versions beforehand. Here's how to generate multires images:

1260 pixels in width:

760 pixels in width:

512 pixels in width:

Find out more on implementing Responsive Images with Uploadcare in our blog.

Step 4. Check Performance

You can compare page load time and traffic optimization with Uploadcare CDN and without. Use tools like chrome-devtools for local tests. Play around with the image quality and find a sweet spot for the best visual traffic compression results.

Note that the first request for each media file over Media Proxy URL will copy it to Uploadcare CDN. Therefore, there won't be a performance improvement yet. However, once it gets copied to our servers, all subsequent requests will fetch the file from the closest CDN node.

Media Proxy Use Cases

We picked a collection of the most popular Media Proxy use cases. These cases are about optimizing traffic, improving load time, and handling your assets the way you need.

Improve Load Time

Media Proxy fetches your assets and delivers them via Uploadcare CDN. That alone improves load time of your assets because they get served from a CDN node best for your client’s location.

When handling media, Media Proxy provides further load time improvement by letting you cut file sizes at no visual quality loss. With images, that can be done via our Image Transformations feature.

Specifically, take a look at the following on-the-fly operations:

  • format, convert images to WebP, PNG or JPEG. It's recommended to use format/auto
  • quality, adjust image quality.
  • resize, adjust image size.

This set of tools can help accelerate your images up to 9x.

Implement Responsive Images

After you set up delivery with Media Proxy, there's just one step to build a responsive design. Responsive images require that you prepare images in different sizes and later list them in the srcset attribute or the <picture> element.

Check out our blog article on Image Transformations that covers responsive techniques.

Cut Traffic Costs

While accelerating your media improves your conversions, using less bandwidth cuts your traffic costs.

The workflow here is quite the same as in the load time section: you control media formats, quality levels, and dimensions. It helps you get smaller files without any visual quality loss.

Migrate To The Cloud

A possible case is that you already use a File API or cloud storage for your assets. In both cases, it is easy to migrate. Set up Media Proxy, make a list of your asset URLs, and replace thm with their optimized versions.

Your existing media assets may be transformed on-the-fly with the File API. Read more on Image Transformations here in docs. Learn how to use them with Media Proxy.

Possible Errors

Here's a list of errors you might get when using Media Proxy:

[HTTP 400] Domain <> is not registered

You did not register a Media Proxy domain for your sites by dropping us a line at

[HTTP 400] Domain <> is not allowed

You tried fetching a file from a domain that was not allowed. Check settings or contact us to add the domain as allowed for your account.

[HTTP 400] Failed to parse file URL

Your prefix was added to an invalid URL. Consider checking that URL.

[HTTP 404]

You tried fetching an unreachable file. Consider checking its URL.

[HTTP 502] 'is_ready' timeout

A problem occurred when trying to upload a file to our storage. Try again later and if it didn't help you always can contact us.

Other errors

Since Media Proxy uses the from_url method, you can also get general errors related to the Upload API or specific to the from_url method.