Enter a number and pick its source base (2 to 36); the converter instantly shows the value in binary, octal, decimal, hexadecimal and any custom target base. Digits beyond 9 use letters a-z, so base 36 covers the full alphabet. A leading minus sign is supported for negative numbers.
Unlike converters built on parseInt, which silently loses precision above 2^53, this tool implements its own base parsing and formatting on top of JavaScript BigInt, so numbers with hundreds of digits convert exactly. Everything runs locally in your browser and nothing is uploaded.