20 tools
Developer Utilities
A set of everyday utilities that don't fit neatly into a single data format: generating unique identifiers, testing and building regular expressions against real input, converting between Unix timestamps and human-readable dates or across time zones, converting numbers between bases and Roman numerals, converting between CSS px/rem units, and looking up DNS records, WHOIS registration data, IP geolocation, and domain age.
Tools
UUID Generator01Generate cryptographically random UUID v4 values, in bulk.Regex Tester02Test regular expressions against real input with live match highlighting.Regex Generator03Build a regular expression from structured building blocks.Timestamp Converter04Convert between Unix timestamps and human-readable dates.Unix Timestamp Converter05Convert a Unix timestamp to a date, or a date to Unix time.Time Zone Converter06Convert a date and time between time zones, with real DST handling.Roman Numeral Converter07Convert between numbers and Roman numerals, in both directions.Binary Converter08Convert between binary, octal, decimal, and hexadecimal.DNS Lookup09Look up A, AAAA, MX, TXT, and other DNS records for a domain.WHOIS Lookup10Look up a domain's registrar, registration dates, and name servers.IP Lookup11Look up approximate geolocation and network info for an IP address.Domain Age Checker12Find out how old a domain is, from its WHOIS creation date.PX ↔ REM Converter13Convert between px and rem with a configurable root font size.Octal Converter14Convert between octal, binary, decimal, and hexadecimal.API Tester15Send HTTP requests and inspect the status, headers, and response body.Cron Expression Generator16Build and validate cron expressions, with a plain-English reading and the next run times.OpenAPI Validator17Validate an OpenAPI 3.x document in JSON or YAML and see errors and warnings by path.CORS Tester18Check which CORS headers an endpoint returns and whether a browser will allow the request.MIME Type Lookup19Look up the MIME type for a file extension, or the extensions for a MIME type.Semver Checker20Compare semantic versions and check whether one satisfies an npm-style range.