Unix & Linux Tools
Practical calculators and utilities for system administrators, developers, and anyone who lives at the command line.
IPv4 Subnet Calculator
Calculate IPv4 network, broadcast, host range, and address counts.
ipv6-subnet-calculatorIPv6 Subnet Calculator
Calculate IPv6 network prefixes and address space.
chmod-calculatorChmod Calculator
Convert Unix permissions between octal and symbolic notation.
cron-calculatorCron Calculator
Build standard five-field cron expressions.
umask-calculatorUmask Calculator
Calculate default permissions from a Unix umask.
unix-timestampUnix Timestamp
Convert Unix timestamps to readable dates.
epoch-converterEpoch Converter
Convert dates and times to Unix epoch values.
regex-testerRegex Tester
Test regular expressions directly in your browser.
cidr-calculatorCIDR Calculator
Calculate IPv4 CIDR network information.
dns-lookupDNS Lookup
Look up DNS records using DNS-over-HTTPS.
dns-checkDNS Check
Check nameservers, core DNS records, email records, and common DNS settings.
ssl-checkerSSL Checker
Inspect TLS certificates using OpenSSL.
ip-lookupIP Lookup
Look up public IP and basic network information.
dns-propagationDNS Propagation
Compare DNS answers from public resolvers.
speedtestInternet Speed Test
Measure browser latency, download speed, and upload speed.