Browser-based web tools
Karu Tools
Karu Tools is a free collection of browser-based utilities for everyday tasks — counting characters, calculating ages, splitting bills, and more. No sign-up required.
Recommended tools
All toolsCharacter CounterEdit text while counting characters, characters without whitespace, lines, paragraphs, and manuscript-page estimates directly in your browser, then copy the result.Japanese Year / Date Era ConverterConvert Gregorian years and dates into Japanese era notation from Meiji onward, including Reiwa, Heisei, Showa, and exact era transition dates.Age & Days Since Birth CalculatorCalculate age, days since birth, the next birthday, and days remaining from a birth date and reference date.Split Bill CalculatorSplit a total amount by the number of people and round each share by 1, 10, or 100 yen.