Quibr

Quibr (quibr.so) is an AI social media agent for newsletter creators. It watches your newsletter's RSS feed. When a new edition goes out, it writes posts for X, LinkedIn, Threads and Facebook from it, spreads them across the week and publishes them. You set it up once and go back to writing.

Posts are written against posts you have already published, with a separate voice persona for each platform, so they sound like you and not like generic AI. You choose how much control to keep: approve every post, let posts go out unless you step in during an approval window, or let the agent run on its own, with an emergency stop.

It works with any newsletter that has an RSS feed, including beehiiv, Substack, Ghost, Kit and Mailchimp. Quibr is $29 a month for everything, with a seven-day free trial. Formerly Letterly.