Convert text to binary, hex, decimal, or octal and back. Type on either side and the other updates. Text is read as UTF-8, so emoji and accented characters survive the round trip.
Computers store text as numbers. Each character maps to one or more bytes, and a byte is just eight bits - eight 1s and 0s. The letter A is 65, which is 01000001 in binary, 41 in hex, and 101 in octal. This tool encodes your text to UTF-8 first, then shows each byte in the base you pick. ASCII characters take one byte each, while emoji and accented letters take two to four, so they still round-trip cleanly.
Type text on the left to see it encoded on the right, or paste binary, hex, decimal, or octal on the right to decode it back to text. Switch between bases with the chips up top. The separator control changes how output values are joined - a space, a comma, or nothing at all. Binary and hex can be glued together with no separator and still decode, since each byte is a fixed width.
Working through a binary or ASCII puzzle. Reading a hex dump or a byte stream by hand. Teaching or learning how character encoding works. Building test fixtures that need a known byte sequence. Decoding a string of numbers someone sent you to see what it actually says.