Open any file to see its bytes as hex and ASCII side by side, then edit, insert or delete bytes, search for hex patterns or text and read values with the data inspector. The file is read locally and never uploaded.
Last updated:
sample.pngDrop any file here to open it. Nothing is uploaded.
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How to use the Online Hex Editor
Open a file with the Open file button or drop it on the editor. A small PNG sample is loaded so you can try it right away.
Move around with the arrow keys, Page Up/Down and Home/End, or use Go to offset to jump to a position such as 0x400.
Edit bytes: click a hex cell and type hex digits, or press Tab to switch to the ASCII column and type text. Changed bytes turn orange.
Search for a hex sequence like 49 48 44 52 (?? matches any byte) or switch to Text, then use Find next and the previous arrow.
Read values at the cursor in the data inspector and switch between little-endian (LE) and big-endian (BE).
Download the file to save your changes; use Undo (Ctrl+Z) to step back at any time.
Reading a hex view
Each row starts with the offset: the position of its first byte, counted from 0 and written in hexadecimal. With 16 bytes per row the offsets go 00000000, 00000010, 00000020 and so on, so the byte under column 0A in row 00000010 sits at offset 0x1A (26 in decimal). The middle columns show every byte as two hex digits and the right column shows the same bytes as ASCII characters.
One hex digit encodes 4 bits, so a byte (8 bits) always takes two digits: 00 = 0, 7F = 127, FF = 255. To convert a two-digit value to decimal, multiply the first digit by 16 and add the second: 4E = 4 × 16 + 14 = 78, which is the letter N.
Common file signatures (magic bytes)
Most formats begin with a fixed byte sequence that identifies them regardless of the file name. The editor recognises these automatically; you can also search for them.
Format
First bytes (hex)
As text
PNG
89 50 4E 47 0D 0A 1A 0A
.PNG....
JPEG
FF D8 FF
...
GIF
47 49 46 38 39 61
GIF89a
PDF
25 50 44 46 2D
%PDF-
ZIP, DOCX, XLSX, APK
50 4B 03 04
PK..
GZIP
1F 8B
..
Windows EXE / DLL
4D 5A
MZ
Linux ELF
7F 45 4C 46
.ELF
WAV
52 49 46 46 ?? ?? ?? ?? 57 41 56 45
RIFF....WAVE
WebAssembly
00 61 73 6D
.asm
SQLite 3
53 51 4C 69 74 65 20 66 6F 72 6D 61 74 20 33 00
SQLite format 3.
Keyboard shortcuts
Key
Action
0-9, A-F (hex column)
Overwrite the byte at the cursor, one digit at a time
Any character (ASCII column)
Overwrite with that character's UTF-8 bytes
Tab
Switch between the hex and ASCII columns
Arrows, Page Up/Down
Move the cursor; hold Shift to select
Home / End, Ctrl+Home / Ctrl+End
Start or end of the row, start or end of the file
Delete
Delete the selected bytes (the file gets shorter)
Ctrl+Z / Ctrl+Y
Undo / redo
Ctrl+A, Ctrl+C, Ctrl+S
Select all, copy selection as hex (or text in the ASCII column), download
Tip: before patching an executable or a document, keep a copy of the original. Overwriting keeps every offset in place, while inserting or deleting bytes shifts everything after the cursor, which can break formats that store absolute offsets, such as ZIP directories or PDF cross-reference tables.
Frequently asked questions
What is a hex editor?
A hex editor shows the raw bytes of a file as hexadecimal numbers (00 to FF) instead of interpreting them as text or an image. It lets you inspect file headers, patch individual bytes, repair corrupted files and understand binary formats that ordinary editors cannot open.
Is my file uploaded to a server?
No. The file is read into your browser's memory with the File API, edited there and saved with a download. Nothing is sent over the network, so the editor also works offline once the page has loaded.
How do I edit a byte?
Click the byte in the hex column and type two hex digits (0-9, A-F); the cursor moves to the next byte automatically. To type characters instead, press Tab or click the ASCII column. Use Delete to remove bytes and the Insert box to add new ones.
What is the difference between little-endian and big-endian?
They are the two orders for storing multi-byte numbers. Little-endian (used by x86 and ARM processors and formats like BMP and WAV) stores the least significant byte first, so 01 00 is the number 1. Big-endian (used by PNG, JPEG and network protocols) stores the most significant byte first, so 00 01 is 1. The inspector shows both by switching LE and BE.
Why do some bytes show as a dot in the ASCII column?
Only printable ASCII characters (byte values 32 to 126) are shown as text. Control codes, zero bytes and values above 127 are displayed as a dot so the column stays aligned; their real value is still visible in the hex column.
How large a file can I open?
Files up to 1 GB can be opened, limited by your browser's memory. Scrolling stays fast because only the visible rows are drawn. Searching very large files takes longer, since every byte is scanned in the page.
Can I search with wildcards?
Yes. In Hex mode, ?? stands for any single byte, so 50 4B ?? ?? finds every ZIP signature followed by any two bytes. In Text mode the search is UTF-8 and ignores letter case unless you tick Match case.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.