Sync or crosspost posts, pages or custom post types between blogs or sites in a WordPress Multisite environment

Import VK

Importing VKontakte (vk.com) posts into your WordPress site.

Automattic

Matthias Pfefferle

Jeremy Herve

Brandon Kraft

Ryan C.

ATmosphere

Share your WordPress posts on Bluesky and the wider AT Protocol network — and let conversations there come back as comments on your site.

Alis

JournalPress

A cross-poster supporting Dreamwidth and similar (i.e., LiveJournal-based) sites.

OzTheGreat

In a multisite environment, enables syncing or crossposting of posts, pages, or custom post types from any blog to any other blogs. 
The crossposted articles have exactly the same properties as the original except for the permalink 
which links back to the original.
The initial idea and some of the functionality is heavily borrowed from 
Code For The People’s Aggregator plugin https://github.com/cftp/aggregator/. Unfortunately, that hasn’t been updated 
in years, it’s vastly too complicated, the admin side of things is very clunky and it’s a bit slow. This plugin uses 
some of its methods as a base but has a much more streamlined admin process. We have maintained the same post meta 
field names so this plugin should be 100% backwards compatible.

Alternatives to WPArtisan Multisite Crossposter

Top alternatives