Compare the evidence a tool gives you
The right tool depends on the failure you need to investigate. A host response, a DNS answer, a redirect chain and a browser identifier are different observations. Use a controlled input and keep the raw output before choosing a tool.
The previous benchmark scores have been withdrawn because their underlying records were not available. The guides below now provide evaluation procedures. They do not claim that WebsiteDown.org or another provider has passed those tests or earned a numerical ranking.
Website down checkers
Does the tool request the exact page or only the origin? Test location coverage, observation timestamps and downloadable evidence.
HTTP status checkers
Compare HEAD and GET, a 403, a redirect and a failing subpath with known responses.
DNS lookup tools
Check resolver identity, NXDOMAIN versus empty answers, CNAME chains and TTLs.
Redirect checkers
Inspect the first hop, relative destinations and loops instead of judging only the final 200.
IP checkers
Compare address family, network route and the source address seen by the service you are investigating.
User-agent checkers
Separate raw browser information, parser guesses and unknown fields for a reproducible bug report.
Make the result reusable
For every test, record the tool URL, UTC time, exact input, expected result, observed result and saved output. Use safe test endpoints you control. A vendor documentation claim and your own measurement should remain separate in the report.
WebsiteDown.org operates the tools linked from these guides. Our editorial policy explains this relationship and the standards for future comparisons. For an example of recorded output rather than a score, inspect the example.com measurement.