Does ContentSync sync in both directions?

No. Articles go one way, from the source site to the site the plugin is installed on. The source is the original.

Do I have to install anything on the source site?

No. ContentSync reads the source through the Joomla Web Services API, which is part of Joomla. You only create an API token there. Your first sync shows how.

Can the two sites run different Joomla versions?

Yes. The target site needs Joomla 5 or 6. What can be copied depends on the version of the source site. The main difference: a Joomla 5 source hands over the intro and full text as one text. See Joomla 5 and Joomla 6.

What happens when I edit a copied article on the target site?

Your change stays until that article changes on the source. Then the copy is overwritten with the source version. Edit on the source.

What happens when I delete an article on the source?

In the free edition the copy stays where it is. In PRO you choose: move it to the trash, unpublish it or delete it permanently. See Removed articles and incremental sync.

How often does it run?

As often as you tell the Joomla Task Scheduler. Once an hour suits most sites. A run where nothing changed is quick, because unchanged articles are skipped.

Can I sync from more than one site?

Yes. Add the task once for every source site. You can also add it several times for the same source, for example one task per category.

Can I sync to more than one site?

Yes. Install ContentSync on every site that should receive the articles. They can all read from the same source, with the same token or each with its own.

Does it copy categories, menus or users?

No. It copies articles, with their images and, in PRO, their tags, custom fields and files. The categories, tags, fields and users have to exist on the target site. ContentSync connects to them, it does not create them.

Does it work with multilingual sites?

An article keeps its language. In PRO you can limit a task to certain languages. The links between translations, which Joomla calls associations, are not copied.

What about articles that are already on both sites?

ContentSync only knows the articles it copied itself. An article that you copied by hand earlier is not recognised as the same one. When an article with the same alias already exists in the target category, ContentSync links the two instead of making a second one.

Are the images copied or only linked?

Copied. The images of an article are downloaded to the target site, in the same folders. The copy does not depend on the source site to show its pictures. See Images, documents and media.

Is it safe to sync from a site I do not manage?

That is what it is built for. Scripting is filtered out of the text, files are checked before they are written, and an article with an unknown access level is never shown to everyone. See Security.

What is the difference between Free and PRO?

The free edition copies articles and images into one category. PRO adds filters, mappings, custom fields, documents and the handling of removed articles. The full table is in Free and PRO.

Do I lose my settings when I go from Free to PRO?

No. Install PRO over the free edition. Your tasks keep their settings, and nothing is copied twice.

Does it slow my site down?

Not for visitors. The work happens in the scheduler, in the background. A first run on a large site takes a while, because every article and image is new. After that a run only handles what changed.