Free website tools
Quick checks for when something looks wrong with a website, a domain or a cron job. No sign-up needed.
Is it down?
Check whether a website is down for everyone or just you. We request the URL from Cloudflare's network and show the HTTP status and response time.
SSL certificate checker
Check a website's SSL/TLS certificate: when it expires, who issued it, which host names it covers and whether it matches the domain. Free, no sign-up.
Domain expiry checker
Look up when a domain name's registration expires, straight from the registry's RDAP record. Works for .com, .net, .org, .io, .dev, .co.uk and most other TLDs.
Redirect & header checker
See every redirect hop, status code and response header for any URL. Find redirect chains, loops and missing HTTPS or security headers.
DNS lookup
Look up the DNS records of any domain: A, AAAA, CNAME, MX, NS, TXT, CAA and SOA, answered live by Cloudflare's public resolver 1.1.1.1.
Cron expression explainer
Paste a cron expression to see what it means in plain English and the next times it will run. Supports ranges, steps, lists, names and @daily.
Uptime / SLA calculator
Convert an uptime percentage like 99.9% into allowed downtime per day, week, month and year, or turn downtime into an uptime percentage.
HTTP status code reference
What every HTTP status code means, why servers send it, how to fix it and what it means for uptime monitoring.
Want these checks to run around the clock? Start monitoring free — 10 monitors, no credit card.