Free Online Calculators, Converters & Developer Tools
23 fast, private utilities in one place. Every tool runs in your browser, so there is no sign-up and nothing you type is uploaded.
Date & Time
Date Calculator
Find the difference and business days between two dates, or add and subtract years, months, weeks, and days.
Universal Calendar
Browse any month from 1900 to 2100 with ISO 8601 week numbers and today highlighted.
Time Zone Converter & Meeting Planner
Convert a reference time across world cities with DST and UTC offsets, then scrub a 24-hour slider to find overlapping working hours.
Unit Converters
Length Converter
Convert between metric, imperial, and nautical units of length.
Area Converter
Convert square units, acres, and hectares.
Volume Converter
Convert liquid and cubic volumes, including US and UK fluid ounces.
Weight & Mass Converter
Convert between metric and imperial units of mass.
Temperature Converter
Convert Celsius, Fahrenheit, and Kelvin with the formula shown for every conversion.
Time Converter
Convert durations from milliseconds up to standard 365-day years.
Power, Energy & Electrical
Convert power and energy units, or solve Ohm's law, power, and energy relationships.
Development Tools
Text & Code Formatter
Prettify and validate JSON and XML documents.
Regex Tester & Explainer
Test regular expressions against sample text with live match highlighting and a token-by-token explanation.
Base64 & URL Encoder
Encode and decode text to and from Base64 or URL-safe percent-encoding.
UUID & Password Generator
Generate v4 UUIDs and strong, customizable random passwords using your browser’s secure random source.
Mock Test Data
Finance & Markets
Currency Converter
Convert between 30+ world currencies using daily reference rates from the European Central Bank.
National Stock Indices
Benchmark indices, exchanges and trading hours by country, with a searchable list of top constituents.
Top Banks Directory
Leading commercial banks by country with headquarters, strengths and SWIFT/BIC code formats.