Note: “Photon” is now part of Site Accelerator.
For general features and FAQs, please see our CDN features here.
How to Activate the Site Accelerator
- In your site’s dashboard, go to Jetpack → Settings → Performance.
- In the Performance & speed section, toggle on Enable site accelerator.
How Site Acceleration Works
Image load times
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 your database.
- It 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_downsizefilter: 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 and new posts alike and can be turned on or off easily, applying the changes in just a few minutes total.
- Browsers that support the WebP image format will be served WebP image data (note that the file extension won’t change).
Static file load times
- It filters the URLs of assets that are loaded with every WordPress page.
- It only acts on assets shipped with WordPress core, Jetpack, and WooCommerce. Theme and plugin assets are not supported at this time.
- No cache invalidations. Currently, static assets are 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 “cache busters,” will not work.
- It is not possible to automatically purge all images from a site. If there is an image no longer on your server that 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
i3.wp.com. Since images can only be purged manually by individual URL, there is a limit to the number we can purge.
- We only fetch, resize, and serve GIF, PNG, JPG, and WebP images from servers that listen on port 80 for HTTP and port 443 for HTTPS. This applies to 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 1,000px wide and you ask for Jetpack to make it 5,000px, we will serve the original 1,000px image. Upscaled images are usually of poor quality, and we want to avoid that.
- If your server takes longer than 10 seconds when an image is being retrieved for our CDN, the process will time out and your image will appear to be broken. Try to upload a differently-named image with a smaller dimension or 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 placed all over the world, and which server will load your image is dependent on a variety of factors, including the visitor’s location.
- Site Accelerator does not support animated PNGs.
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 developer.wordpress.com.
Site Accelerator is only allowed to be used by sites hosted on WordPress.com or on Jetpack-connected WordPress sites. If you move to another platform or disconnect Jetpack from your site, please also switch to another image CDN service. Any abuse of Jetpack or violation of the WordPress.com Terms of Service could result in the suspension of your site from WordPress.com-connected services, including Site Accelerator.
Can I use your Site Accelerator with audio or video files?
Site Accelerator does not serve audio (.mp3, .wav, .flac, etc.) or video (.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 1,000px. 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 might be narrower than the previous one. One of the benefits of this is that we will automatically resize your images so they don’t exceed the width supported by your theme.
What happens to my images if I disable Image Accelerator?
No worries! Your images will continue to work just fine, they will just start loading from your webhost’s server again instead of ours. Please note that it could take a few minutes for these changes to take place.
Once Site Accelerator has been enabled, can I delete the images from my server?
No! Your images need to remain on your server for the CDN to work correctly. Any images that are removed from your server will eventually “expire” and be removed from the CDN.
I enabled/disabled Site Accelerator and the images are broken
- As a first step, wait a few moments and then load your site in a completely different web browser than you normally use to make sure it’s not just your browser cache interfering with the URL change. It can take a few minutes for these changes to be reflected on your entire site.
- Next, check that your Jetpack connection is working properly.
- Still not working? 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. You can find out which plugin is the culprit by enabling each plugin one by one and checking images after each one.
- Finally, if it still isn’t working after disabling your 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.
- No luck? Please reach out to us for more support.
Still need help?
Please contact support directly. We’re happy to lend a hand and answer any other questions that you may have.
Site Accelerator is deactivated by default. You can toggle the feature on or off under the Performance & speed section from Jetpack → Settings → Performance in your dashboard.
|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, WordPress.com user ID, WordPress.com username, WordPress.com-connected site ID and URL, Jetpack version, user agent, visiting URL, referring URL, timestamp of event, browser language, country code.
|Site Owners / Users
We track when, and by which user, the feature is activated and deactivated.
|Data Synced (Read More)|
|Site Owners / Users
We sync a single option that identifies whether or not the feature is activated.