It's a free Google Sheets / Apps Script you just paste to your sheet, and it turns the sheet into a full CRUD. It's kind of rate limited though but completely free!
Edit: I've thought about creating a company around Sheets before, and the problem is that once you get to the "willing to pay" stage, you also kind of outgrow Sheets. I'd rather migrate to Turso, Cloudflare D1, or Pocketbase instead of staying with Sheets or SpreadAPI, because of the limitations.