All tools
Network tools for technicians
Free, no sign-up, no tracking. Every tool also works from the command line.
- My IPPublic IPv4/IPv6 address, reverse DNS, network and country.
curl tools.otw.solutions - Domain lookupRegistrar, DNS hosting, web hosting, mail provider, SPF/DMARC/DKIM.
curl tools.otw.solutions/dns/example.com - Super CheckBetaOne input for MX, SPF, DMARC, DKIM, BIMI, MTA-STS, blacklists, DNS records, whois and HTTPS, with pass/fail checks.
curl tools.otw.solutions/check/mx:example.com - DNS DiggerEvery DNS record of a domain that can be found, as a zone file, for moving to a new DNS provider.
curl tools.otw.solutions/dig/example.com - SSL/TLS checkCertificate, chain, expiry and TLS versions for HTTPS, SMTP/IMAP STARTTLS, LDAPS and any other port.
curl tools.otw.solutions/ssl/example.com:443 - Port checkWhich ports of your own public IP are reachable from the internet?
curl tools.otw.solutions/ports/443,3389 - Blacklist checkIs an IP or a domain’s mail server listed on Spamhaus, SpamCop, Barracuda & co.?
curl tools.otw.solutions/blacklist/example.com - DNS propagationCompare a record across public resolvers and the authoritative nameservers.
curl tools.otw.solutions/propagation/example.com/MX - Microsoft 365 tenantTenant ID, name, region, managed/federated and the M365 DNS records of a domain.
curl tools.otw.solutions/m365/example.com - Subnet calculatorIPv4/IPv6 network, mask, host range and splitting into smaller subnets.
curl tools.otw.solutions/subnet/10.0.0.0/22 - Regex testerTest ECMAScript (JavaScript) regular expressions live, with groups, replace preview and ready-made IT patterns.
runs in your browser - Cron explainerCron expression in plain English, next run times in any time zone, systemd OnCalendar equivalent.
curl tools.otw.solutions/cron/0_3_*_*_1-5 - Linux cheat sheetDebugging commands for AlmaLinux / RHEL, with Debian / Ubuntu equivalents.
curl tools.otw.solutions/linux/selinux - Docker cheat sheetContainers, logs, exec, disk space, networking, Compose and exit codes.
curl tools.otw.solutions/docker/logs - Password generatorRandom passwords and passphrases, generated in your browser.
curl tools.otw.solutions/pw