Free tools for the questions that come up mid-incident

Why these tools exist

Most of what an on-call person types at the start of an incident is a handful of small lookups. Is the site down for everyone or just for me? When does that certificate expire? What does the MX record say right now? What does the cache header on this response look like? We built these utilities for ourselves while running monitors, and we left them open because they are useful whether or not you ever become a customer.

The tools that touch a live target, such as the response-time test and the site status check, send real requests from our checkers in two regions, so the answer is not coloured by your own network or resolver cache. The calculators (uptime, cron, subnet) run in the page and send nothing anywhere. The DNS tools query public resolvers and show what a recursive lookup returns, with a note on what the same query would look like in dig on your own terminal.

Every tool is rate limited a little, which keeps it free for everyone and keeps it from being used to probe targets. If you find yourself running the same lookup daily, that is the signal to turn it into a monitor: a DNS monitor will tell you when a record changes, an SSL monitor will warn at 30, 14 and 7 days, and a domain monitor will watch the registration clock. The monitoring types overview lists them all.