Does my data get uploaded anywhere?
No. Everything runs locally in your browser and nothing is sent to a server.
Is this free to use?
Yes. It is completely free, with no account, no signup, and no usage limits.
Does it work on a phone?
Yes. The page runs in any modern mobile browser, on iPhone and Android alike, with no app to install.
What is hex 1B in octal?
33. That is the ESC control character (decimal 27), which is why an ANSI escape sequence is written \033[0m in shell and C, and \x1b in languages that prefer hex. Both spell the same byte.
Why can I not convert hex to octal digit by digit?
Because a hex digit carries four bits and an octal digit carries three. They do not line up until 12 bits, so the safe route is to convert the whole value, which is what this tool does with arbitrary-precision integers.
What is the largest byte value in octal?
377, which is FF in hex and 255 in decimal. Every byte fits in three octal digits, and the leading digit never goes above 3 because the top group is only two bits.
Does it accept a 0x prefix?
Yes, and it also accepts upper or lower case letters. 0xFF, 0xff and ff all parse to the same value and convert to 377.
Can I convert several hex values at once?
Yes. Separate them with spaces, commas or new lines and each is converted independently, in order, so a row of hex bytes becomes a row of octal ones.