Hex Viewer
Any file's raw bytes — offset, hex, ASCII, and its magic number.
About this viewer
Drop in any file and read its opening bytes in the classic three-column dump: hex offset, sixteen bytes per row, printable ASCII alongside. The magic-number check names what the file actually is — PNG, PDF, ZIP, executable — regardless of what its extension claims. First 64 KB shown, which covers every header that matters.
Magic numbers: files' honest signatures
Most formats open with a fixed signature: PNG files start with byte 0x89 then "PNG", PDFs with "%PDF", ZIPs with "PK" (Phil Katz's initials — and every .docx, .xlsx and .apk is secretly a ZIP, which the dump reveals instantly). Extensions are labels anyone can edit; magic numbers are what software actually trusts, so a "invoice.pdf" that starts with MZ (a Windows executable) is telling you everything you need to know. The ASCII column earns its keep on text-adjacent formats — you can watch a UTF-8 BOM, spot embedded strings in binaries, and see exactly why Base64 exists the moment binary bytes meet a text channel. Checksums fingerprint whole files; this shows you their faces.
Frequently asked questions
What is a magic number?
A fixed opening byte sequence that identifies a format — %PDF for PDFs, PK for ZIPs, 0x89-PNG for PNGs. Software trusts these over extensions, and so should you.
Why do docx files show as ZIP?
Because they are ZIPs — Office documents are zipped folders of XML. The PK signature in the dump is the honest answer; rename one to .zip and look inside.
Is my file uploaded?
No — the file is read locally and only the first 64 KB is even loaded into memory. Safe for sensitive files.
What does the · in the ASCII column mean?
A byte with no printable ASCII form (control bytes, high values). The dot keeps the column aligned so printable runs — embedded text — stand out.