What it is
Quibr (quibr.so), formerly Letterly, 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.

Who it's for

• Solo newsletter creators with 500 to 5,000 subscribers who publish every week.

• Writers on beehiiv, Substack, Ghost, Kit or Mailchimp, or any newsletter with an RSS feed.

• Founders and indie hackers who write a build-in-public newsletter.

The problem
Writing your newsletter is just the start. The real work begins when you need to turn it into posts, threads, and shareable pieces that attract new readers. Doing this manually is slow, repetitive, and mentally draining, which makes consistent growth nearly impossible.

How it works

1. Connect your newsletter's RSS feed once.

2. Add a voice persona for each platform, built from posts you have already published, so the posts sound like you.

3. When a new edition goes out, Quibr writes the posts and schedules them across the week.

4. Choose how much control to keep: approve every post, step in during an approval window, or let it run on full auto, with an emergency stop.

Price
$29 a month for everything, with a seven-day free trial.