ZoneVouch checks a domain at the registry itself, then shows the registrar's real register and renewal price, not a teaser price that doubles next year.
Each check ends in a diligence report. The part I care most about is the list of what it could not check, because a report that hides its gaps is worse than no report.
Buying is gated: the tool never buys a domain on its own. It prepares the decision and a person makes it.