Extension:Parsoid

This PHP extension populates and coordinates a cache with content generated by Parsoid to make cached pages immediately available for users. It is no longer in use; it has been replaced with RESTBase.

Extension:Parsoid is not actually the Parsoid service. If you are trying to install Parsoid, you should follow the instructions at Extension:VisualEditor.

Required for MediaWiki 1.23 users of VisualEditor
For MediaWiki 1.23 users, it also provides a styling module that is a dependency of VisualEditor, so this extension must be installed for VisualEditor to work on MediaWiki 1.23. From MediaWiki 1.24 onwards, this styling module was upstreamed into MediaWiki itself, and so this extension is not required (although you must still install the Parsoid server itself) unless you have a deployed Varnish cache.