Convert between binary, octal, decimal, hex and base 36 with exact BigInt arithmetic, a two's complement view at 8 to 64 bits, and prefixes like 0x and 0b understood on input.
JavaScript's Number is a 64-bit float and loses integer precision above 2^53, which is smaller than a 64-bit id or a hash. BigInt has no limit, so a long hex string converts exactly instead of ending in a run of zeros.
The bit pattern a register of the chosen width would hold, which is how a negative number is stored and why -1 reads as 0xFF in eight bits. If the value needs more bits than the width, the tool says so and shows the wrapped value.
Yes. A 0x, 0b or 0o prefix sets the base regardless of the picker, and underscores or spaces between digits are ignored, so a number copied out of source code works as it is.