Free DevOps & Monitoring Tools
Browser-based tools for developers, sysadmins, and SREs. No signup, no install, no tracking.
Cron Expression Builder
Build cron expressions visually. Select fields, use quick presets, and preview the next 5 scheduled runs.
Open tool →Cron Expression Validator
Paste a cron expression and see whether it's valid, what it means in plain English, and when it fires next.
Open tool →Uptime Calculator
Convert uptime percentages (99.9%, 99.99%) to allowed downtime per day, month, and year.
Open tool →SSL Certificate Checker
Inspect any domain's SSL certificate: issuer, expiry date, SANs, signature algorithm, and chain details.
Open tool →Domain WHOIS Lookup
Look up domain registration details: registrar, creation date, expiry, nameservers, and DNSSEC status.
Open tool →HTTP Status Checker
Send a request to any URL and see the HTTP status code, response headers, redirect chain, and timing.
Open tool →Port Checker
Test whether a specific TCP port is open on a remote host. Useful for firewall and service diagnostics.
Open tool →Response Time Tester
Measure how long a URL takes to respond. See DNS, connect, TLS, and total time breakdowns.
Open tool →DNS Lookup
Query DNS records for any domain: A, AAAA, CNAME, MX, TXT, NS, and SOA records.
Open tool →MX Record Lookup
Check the mail exchange (MX) records for a domain and see which mail servers handle its email.
Open tool →HTTP Headers Checker
View the full list of HTTP response headers returned by any URL. Check security headers, caching, and CORS.
Open tool →