View and edit binary files in hexadecimal with ASCII sidebar, search, and byte-level editing capabilities.
Hex Editor lays out a binary file as ordered, two-digit hexadecimal byte values with a neighboring ASCII sidebar. It lets you search for sequences and replace values at individual byte positions while keeping the surrounding binary visible. The usual mistake is to read the ASCII column as a faithful text decoding. It is only a byte-by-byte ASCII aid: non-ASCII encodings do not map one byte to one displayed character, while occasional readable words can occur inside an otherwise binary format.
A concrete input and expected output from the current implementation.
Input
48 65 6C 6C 6F
Expected output
ASCII sidebar for those bytes: Hello
Each hexadecimal pair is one byte. Values 48, 65, 6C, 6C, and 6F represent the ASCII characters H, e, l, l, and o, respectively.
Each pair of hexadecimal digits represents one byte, from 00 through FF, and the pairs remain in file order. The adjacent ASCII cell gives a character cue when that byte is printable ASCII. Treat the two columns as alternate views of the same byte, not as separate content. Replacing 6C with 21 changes the corresponding ASCII cue from l to !.
Search helps locate a known run of bytes or an ASCII fragment within the file. A match identifies positions where the same values occur; it does not establish what those bytes mean in the file format. After an edit, compare the surrounding hex and ASCII views so that the intended position changed and adjacent bytes retained their original values.
Sometimes it can provide evidence, but it cannot confirm a type from appearance alone. Compare the opening bytes with an authoritative format specification, and remember that signatures can be absent, shared, nested, or misleading. The editor shows the evidence needed for that comparison; it does not make every arbitrary byte sequence self-describing.
For plain ASCII bytes, a one-character replacement can correspond to one byte. For UTF-8 or another multibyte encoding, the answer is no unless you know the exact encoded byte sequence and any format constraints. Editing only one byte of a multibyte character may create invalid text or alter a different character than intended.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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