Why are private or localhost URLs blocked?
A public URL checker must not fetch internal network targets. Blocking local, private, reserved, credentialed, and non-http destinations reduces SSRF and proxy-abuse risk.
Does this download the full page?
No. It uses status-oriented requests and reports metadata such as status, Location, content type, timing, and final URL. It does not display response bodies.
Can a redirect checker replace real click testing?
No. It verifies status and redirect metadata, but real browsers, logged-in states, geo rules, consent flows, and ad platforms can still behave differently.
Do utility tools upload my payload?
Use the page notes for each tool. Browser-side utilities can generate outputs locally, but the final file or code may still reveal whatever you encode or share.
Why should I test the generated output?
Scanners, printers, file viewers, apps, and platform previews can behave differently, so test the exact downloaded output before using it publicly.
Why might another checker show a different output?
Different tools may use different rounding, assumptions, default rates, methods, formulas, or input timing. Compare the visible method and inputs before relying on the output.