Free local hex & ASCII byte inspector
Read the raw bytes
inside any file.
Inspect any file in hexadecimal and ASCII locally in your browser. Highlight magic bytes, jump to offsets and search patterns without uploading files.
Drop a file here to inspect its bytes.
Or choose a file from your device. Reads 512-byte slices on demand, so even multi-gigabyte files open instantly.
Read-only local inspection. File contents are never executed or uploaded.
Use is subject to our terms. Read the privacy policy.
How to read a hexadecimal view
Every file on your device is a sequence of bytes, each with a value from 0 to 255 (00 to FF in base-16 hexadecimal). This viewer displays your file in three columns:
- Byte offset (
00000000): The starting byte position of each 16-byte row, in hexadecimal. - Hexadecimal bytes: Sixteen two-digit hex values per row. The file’s opening signature bytes (or your latest search match) are highlighted in gold.
- ASCII text (
|…|): Printable ASCII characters (0x20to0x7E), with non-printable binary bytes shown as dots (·) so readable headers like%PDF-,PNG,ftypandPKstand out immediately.
Built for files of any size
Traditional browser viewers crash on large videos, disk images or archives because they read the entire file into memory. File Sniff’s hex viewer uses Blob.slice to read only the visible 512-byte window from your disk whenever you page or jump to an offset.
Learn which header markers identify common formats in our file signatures & magic bytes guide, or get an automatic format report with the file type checker.
Common questions
Can this hex viewer open very large files without crashing my browser?
Yes. Instead of reading the entire file into memory, the viewer uses Blob.slice to read only the current 512-byte window as you page or jump to an offset.
Why are the first bytes highlighted?
Most file formats store their identifying signature—often called magic bytes—at the very start of the file. When you search for a sequence, the highlight moves to the matching bytes.
What do the dots in the right-hand ASCII column mean?
Bytes between 0x20 (space) and 0x7E (~) correspond to printable ASCII characters and are shown directly. Non-printable control bytes and binary values above 0x7E are displayed as . so the column alignment stays fixed.