Support Home > Performance > Site Accelerator (Formerly Photon)

Site Accelerator (Formerly Photon)

Note: “Photon” is now part of Site Accelerator.

Jetpack’s Site Accelerator helps your pages load faster by allowing Jetpack to optimize your images and serve your images and static files (like CSS and JavaScript) from our global network of servers.

How to Activate the Site Accelerator

  1. In your site’s dashboard, go to Jetpack → Settings→ Performance.
  2. In the Performance & speed section, toggle on “

How Site Acceleration Works


Our image CDN (formerly Photon) is an image acceleration and editing service. That means that we host your images from our servers, alleviating the load on your server and providing faster image loading for your readers.

  • It filters content but doesn’t change the database.
  • It currently only acts on images in posts and pages, as well as featured images/post thumbnails via the image_downsize filter. Examples of WordPress functions using the image_downsize filter: the_post_thumbnail_url, get_the_post_thumbnail, get_the_post_thumbnail_url, wp_get_attachment_image, wp_get_attachment_image_src.
  • It will apply to old posts and new ones alike and can be turned on or off easily.
  • If your browser supports the .webp image format, images will be served as .webp (note that the extension won’t change).
  • The CDN detects, optimizes, and caches images that use any of the following image file extensions: gif, jpg, jpeg, and png.

Static Files

We host static assets like JavaScript and CSS shipped with WordPress Core, Jetpack, and WooCommerce from our servers as content delivery network (CDN), alleviating the load on your server.

  • It filters URLs of assets that are loaded with every WordPress page.
  • It currently only acts on assets shipped with WordPress Core, Jetpack, and WooCommerce. Theme and other plugin assets are not supported at this time.


  • No cache invalidations – currently the images are cached “forever” and static assets will be tied to the public version of WordPress, Jetpack, or WooCommerce that you’re using. For images, if you want to “refresh” an image you will need to change its file name. Adding random query arguments, commonly known as cachebusters, will not work.
  • If there is an image you’d like us to purge, please contact us with a direct link to the file as it appears on your site. These will begin with,, or
  • We only fetch, resize, and serve gif, png, and jpg images from servers that listen on port 80 for HTTP and port 443 for HTTPS. This is about 99.99% of the web servers in the world. If you are having issues, please try using the jetpack_photon_reject_https filter.
  • We will not “upscale” an image in most circumstances. If your original image is 1000px wide and you ask for us to make it 5000px, we will serve you the original 1000px image. Upscaled images are usually of poor quality and we want to avoid that.
  • If your server takes longer than 10 seconds to upload the image to our CDN, the upload will time out and your image will appear to be broken. Try to upload a differently-named image with a smaller file size if this happens.
  • It’s not possible to choose or limit where in the world your images will be served from. We have servers all over the world, and which server will load your image is dependent on a variety of factors, including user location.
  • Site Accelerator for images shouldn’t be used alongside plugins that convert images to WebP. Converting images to WebP prior to them being optimized by Site Accelerator may interfere with Site Accelerator’s process for serving WebP images.

Themes and plugins can also use the Photon API to transform images using GET query arguments. Developers will find Photon API examples and documentation on

This is only allowed to be used by sites hosted on, or on Jetpack-connected WordPress sites. If you move to another platform, or disconnect Jetpack from your site, please also switch to another magic image service. Abuse of Jetpack or violation of the Terms of Service could result in suspension of your site from services.

Questions & Answers

Can I use your Site Accelerator with audio or video files?

Site Accelerator does not serve audio (i.e., mp3, wav, flac, etc.) or video (i.e., mp4, wmv, flv, etc.) files. If you’d like to host videos on our CDN, check out our video hosting feature.

How does Site Accelerator determine which dimensions to serve for an image?

It looks at the img element’s width and height attributes and then serves an image resized to those dimensions or to the width of the containing element (whichever is smaller). By default, Jetpack will constrain images to the larger of the size indicated when adding the image to a post or to your theme’s “content width” setting. If one isn’t set, Jetpack will default to 1000px. This is to help ensure that sites are not trying to serve images larger than what the theme intended to be able to display.

Is there any way to keep the “width” and “height” attributes in the CDN-generated HTML?

We remove the width and height arguments to prevent your images from skewing when the resized image doesn’t have the same dimensions as the original. This is particularly important when you switch from one theme to another, and the new theme is narrower than the previous theme. One of the benefits of it is that it will automatically resize your images so they don’t exceed the width supported by your theme.

Troubleshooting tips

I enabled Site Accelerator and the images have disappeared
  • As a first step, check that your Jetpack connection is working properly.
  • As a next step, it is possible that there may be another plugin on your site conflicting with Site Accelerator. Please try to disable all of your plugins except Jetpack, then try checking your images again. If they are displaying properly, we’ll know that another plugin is interfering here. You can find out which plugin is the culprit by enabling each plugin one by one and checking images after each one.
  • If it still is not working after disabling the plugins, it may be the theme. To test this, you can switch to one of the default themes such as Twenty Seventeen.  If the issue is resolved then you know it’s a problem with the theme, and you’ll need to contact the theme author for further assistance.
  • If Site Accelerator is still not working after that, please reach out to us for more support.

Privacy Information

This feature is deactivated by default. If you ever need to deactivate this feature, you can toggle them off under the Performance & speed section from Jetpack → Settings→ Performance in your dashboard.

More information about the data usage on your site

This feature is deactivated by default. If you ever need to deactivate this feature, you can toggle them off under the Performance & speed section from Jetpack — Settings — Performance in your dashboard.

Data Used
Site Owners / Users

While not actively used in the delivery of this functionality, EXIF data may exist (and be accessible to site visitors) in any of the images that you upload to your site.Additionally, for activity tracking (detailed below): IP address, user ID, username, site ID and URL, Jetpack version, user agent, visiting URL, referring URL, timestamp of event, browser language, country code.

Site Visitors


Activity Tracked
Site Owners / Users

We track when, and by which user, the feature is activated and deactivated.

Site Visitors


Data Synced (Read More)
Site Owners / Users

We sync a single option that identifies whether or not the feature is activated.

Site Visitors


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