Disclaimer

geoprims tools are planning, engineering, and education aids.

Not for primary navigation. No geoprims tool is certified for navigation or flight operations. Aviation and drone results do not replace your aircraft's POH/AFM, official charts and publications, a flight briefing, or current regulations.
Not a legal survey. Survey tools are not legal survey determinations. Boundary and title questions need a licensed surveyor.
Check operational values. Verify anything you act on against official sources. Each tool shows its model, accuracy, sources, and assumptions under "How we got this", and warnings name the assumptions a result depends on.
Review status. Tools are marked experimental until they pass the verification bar. Practitioner review status is shown on each domain page.

If a result looks wrong, use "Report a problem" on the tool, or see the known issues.