Is there a free tier, and what's the catch?

It's a real tier, not a countdown.

Free: one post per day. All the connection and pool machinery works, you're limited on posting volume. It's enough to connect an account, build a pool, run a campaign, and see whether the thing does what you want on your actual content.

Paid: $99/month, removes the daily post cap and opens the higher-volume features.

The catch, stated plainly: at one post a day you won't feel the main benefit, which is fan-out across many accounts at volume. The free tier is for verifying it works with your content and your accounts before paying, not for running a business on indefinitely.

No card required to start, and we'd rather you kick the tires properly than sign up blind.

Ran free for about two weeks before upgrading. It was enough to know the clipping worked on my kind of video, which was the only thing I actually needed to find out.