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.
How do I decode a byte array back into text?
Copy the numbers out of your array and paste them here, with or without commas. The tool splits on any whitespace or comma, so [72, 105] pastes as easily as 72 105 once you drop the brackets, and both decode to Hi.
Why does 233 on its own give a replacement character?
Because 233 is a Unicode code point, not a UTF-8 byte. As a byte, 233 is a lead byte that expects continuation bytes after it, and without them the sequence is invalid. The correct UTF-8 bytes for that character are 195 and 169.
Can I mix commas and spaces?
Yes. Tokens are split on any run of whitespace or commas, so a list like 72, 101,108 108 111 parses fine. That means you can paste from almost any source without cleaning up the separators.
What do values below 32 do?
They are control characters. 10 is a line feed and will break the output onto a new line, 9 is a tab, and 13 is a carriage return. 0 is NUL, which decodes to an invisible character. They are decoded literally rather than shown as symbols.
What is the maximum value I can enter?
255, because each value is one byte. Anything larger is rejected with an error rather than being wrapped or truncated, which protects you from silently decoding the wrong bytes.