App Museum
日本語

Free browser tools for development and web work

No sign-up or installation. Your input is processed in your browser and is not sent to a server.

Main categories

  • Tools for everyday development and web work, including formatting, encoding, generation, and validation.
  • Tools for counting, reviewing, and transforming text.
  • Tools for converting units, timestamps, numeric representations, and other formats.
  • Tools for quickly calculating dates, percentages, tax, and other values.
  • Format or minify JSON instantly. Everything runs in your browser — no data is uploaded.
    Developerjsonformatterdeveloper
  • Generate a QR code image from text or a URL and download it as a PNG.
    Convertersqrqrcodegeneratorconverter
  • Calculate 'B% of A', 'A is what % of B' and percent change instantly. Great for discounts.
    Calculatorscalculatorpercentmath
  • Convert length, weight, and volume units between metric and imperial systems.
    Convertersunitlengthweightvolumeconverter
  • Count characters, words and lines in real time. Perfect for social posts and manuscripts.
    Texttextcounterwriting
  • Encode text to Base64 or decode Base64 back to text. UTF-8 aware and runs entirely in your browser.
    Developerbase64encodedecodedeveloperconverter

New tools

  • Test a regular expression against text, highlight matches, and inspect capture groups.
    Developerregexregexppatterntestdeveloper
  • Convert colors between HEX, RGB, and HSL, with a color picker and live preview.
    Developercolorhexrgbhslconverterdeveloper
  • Decode a JWT (JSON Web Token) header and payload. Signature verification is not performed.
    Developerjwtjsontokendecoderdeveloper