Image types, sizes and how images reach your site

Which images are accepted#

The content of the file decides its type, not its name. Accepted: JPEG, PNG, GIF, WebP and AVIF, further limited to what your site accepts: a WordPress site's allowed upload types, and Joomla's Media options (allowed extensions and MIME types, when uploads are restricted).

SVG is never accepted (SVG images are not accepted. Use JPG, PNG, GIF, WEBP, AVIF.): it can carry scripts. Convert such images to PNG. A file that is not an image at all, or a web page, gets its own message (web addresses).

Sizes#

• One image: up to 20 MB, or the site's own maximum if that is lower: WordPress's upload limit, or the maximum size set in Joomla's Media options. A larger image is a missing image: The image is larger than N MB, the most the site accepts.
• The ZIP: 25 MB, 2,000 files, 200 MB unpacked (upload images in a ZIP).
• There is no limit on pixels, but very large photographs fill the allowance quickly: image transfer counts the file size (plans and allowances). Resize them first.

How an image reaches your site#

Images are never sent inside the requests that publish content. Instead:

1. Content Uploader checks each image when the file is checked and keeps it in private storage in the EU, together with a fingerprint of its content.
2. When you publish, your site downloads the image from Content Uploader's storage through a short-lived link (valid for 15 minutes, created just before it is used and never stored or shown).
3. The site checks the file against the fingerprint and its own rules, stores it in its media library, and returns a reference. Content Uploader then sets that reference on the item.

So the site needs outgoing HTTPS access to the storage host. If your host blocks it, you see The site could not download the image from Content Uploader. It needs outgoing HTTPS access to the storage host. (troubleshooting).

An image that many items share is delivered once per site, and a retry never creates a second copy.

Where it is stored#

• WordPress: the media library, as an ordinary attachment (set as the featured image), in the normal uploads folder. In the library it shows as Unattached because it is attached to no post; it is used as the post's featured image.
• Joomla: the images folder, as images/content-uploader/<year>/<month>/<name>-<8 letters>.<ext>. File names are made safe and nothing is overwritten.

Rights the account needs#

• WordPress: the account that approved the connection may upload files (upload_files). Without it no image slot is offered.
• Joomla: the publishing account needs Create in Media. Without it the intro and full article image slots are not offered, and publishing says The Joomla account Content Uploader publishes as cannot add files in Media. Allow it to create files in Media, then retry.

Messages at delivery#

These are shown on the item's result on the Sites page and, when the image was not essential, as a warning (missing images).

Privacy of your images#

Images and ZIPs are stored privately, separated by workspace, and deleted automatically 30 days after upload, together with the staged copies. Once an image has been delivered, Content Uploader keeps only its fingerprint and the site's reference, which is all that is needed to reuse it (data and retention).