Development & programming

Find the hostname of any IPv4 or IPv6 address from its PTR record, and check that the hostname points back to the IP, as mail servers require.

Check whether a website or file is served with gzip, Brotli or Zstandard compression, and how many bytes each one saves.

Check whether a web page on another origin can call a URL from the browser. Sends the CORS preflight and a request, then explains each check.

Convert integers of any size between binary, octal, decimal and hexadecimal.

Convert decimal numbers to binary instantly, including integers of any size.

Convert binary numbers to decimal instantly, including integers of any size.

Convert decimal numbers to octal instantly, including integers of any size.

Convert octal numbers to decimal instantly, including integers of any size.

Convert decimal numbers to hexadecimal instantly, including integers of any size.

Convert hexadecimal numbers to decimal instantly, including integers of any size.

Convert binary numbers to octal instantly, including integers of any size.

Convert octal numbers to binary instantly, including integers of any size.

Convert binary numbers to hexadecimal instantly, including integers of any size.

Convert hexadecimal numbers to binary instantly, including integers of any size.

Convert octal numbers to hexadecimal instantly, including integers of any size.

Convert hexadecimal numbers to octal instantly, including integers of any size.

Convert colors between HEX, RGB, HSL, HSV, HWB, CMYK, LAB, LCH, OKLab, OKLCH, XYZ, CSS color names, ANSI terminal codes and more, with format auto-detection and a live preview.

Convert colors from HEX to RGB instantly as you type, with a live color preview.

Convert colors from RGB to HEX instantly as you type, with a live color preview.

Convert colors from HEX to HSL instantly as you type, with a live color preview.

Convert colors from HSL to HEX instantly as you type, with a live color preview.

Convert colors from HEX to HSV instantly as you type, with a live color preview.

Convert colors from HSV to HEX instantly as you type, with a live color preview.

Convert colors from HEX to HWB instantly as you type, with a live color preview.