What this does
Shows the raw bytes of text or a file in the classic three-column hexdump layout: the offset of each row, the bytes in hexadecimal, and the printable ASCII characters (non-printable bytes appear as a dot). Use it to inspect file headers and magic numbers, spot stray byte order marks and invisible characters, or check exactly what bytes a string encodes to.
Output styles
hexdump -C style groups bytes in eights with the ASCII column between pipes and a final line with the total length. xxd style prints bytes in 16-bit groups with a colon after the offset. Choose 8, 16 or 32 bytes per row and lower or upper case digits. The offsets continue correctly when you start from the middle of the data.
Text and large files
For text, pick the character encoding that is dumped (UTF-8, UTF-16, ASCII, Latin-1). Files up to 100 MiB can be opened; the file is read into memory in your browser and a window of up to 256 KiB is rendered at a time, so large files stay responsive. Use the start offset or the Previous and Next buttons to move through it.
Example
A PNG file begins 89 50 4e 47 0d 0a 1a 0a, which shows as .PNG.... in the ASCII column; a UTF-8 file with a byte order mark begins ef bb bf.
Privacy
Files are read locally by your browser and never uploaded.