Well, when I seach for "semgrep", I get a very nice corporate landing page with a "Book Demo" button. Which is a level of hassle that just isn't worth it for smaller teams, because "Book Demo" usually means "We're going to do a dance to see how much money we can extract from you." Which smaller teams may only want to do for a handful of key tools.

(4 years ago, I was more willing to put up with enterprise licensing. But in the last two years, I've seen way too many enterprise vendors try to squeeze every penny they can get from existing clients. An enterprise sales process now often means "Expect 30% annual price hikes once you're in too deep to back out." The lack of easy VC money seems to have made some enterprise vendors pretty desperate.)

There's also an open source "semgrep" project here: https://github.com/semgrep/semgrep. But this seems to be basically a vulernability scanner, going by the README.

Whereas AST-grep seems to focus heavily on things like:

1. One-off searching: "Search my tree for this pattern."

2. Refactoring: "Replace this pattern with this other pattern."

AST-grep also includes a vulnerability scanning mode like semgrep.

It's possible that semgrep also has nice support for (1) and (2), but it isn't clearly visible on their corporate landing page or the first open source README I found.