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.
Does my spacing matter?
No. Every space, tab and line break is removed before decoding, and the bits are then split into groups of 8. That means you can paste bits in any grouping, or with none at all, and get the same result, as long as the total number of bits is right.
Why is my output garbled?
If the bit count is wrong you now get an error rather than garbled text, so garbling almost always means the input was not UTF-8 in the first place, or the bytes are in the wrong order. Check that each group of 8 bits is one byte of the original encoding.
What is the black diamond with a question mark in my output?
It is U+FFFD, the Unicode replacement character. The decoder emits it when the bytes do not form a valid UTF-8 sequence, for example a lone byte above 127 with no continuation bytes after it. It means the input was not valid text, not that the tool failed.
Can I decode 7-bit ASCII codes?
Not directly. The decoder reads 8 bits per byte, so pad each 7-bit code with a leading zero first. 1001000 becomes 01001000, which decodes to H. Pasting unpadded 7-bit codes shifts every subsequent character.
How many characters should I expect from my bits?
Divide the bit count by 8 to get the number of bytes. That is an upper bound on the characters, because plain ASCII is one byte per character while accents and emoji take two to four bytes each. So 40 bits is 5 bytes, which is 5 characters only if it is all ASCII.