Hex File Editor
Open a local file and examine its actual bytes in 16-byte hex and printable ASCII rows. Enter a decimal or 0x offset to move through the file, then insert, replace or delete a specified byte range. Edits are made in a separate memory copy. Download the resulting binary and a JSON report recording active changes and SHA-256 hashes.
Key features
- View 256 bytes at a time as 16-byte offset, hex and printable ASCII rows
- Insert, replace or delete bytes at explicit decimal or 0x offsets
- Validate byte syntax, range boundaries and file size before each edit
- Undo up to 50 active edits while retaining the untouched original bytes
- Download a new binary and a JSON change log with original and edited SHA-256 hashes
How to use
- Choose a local file up to 8 MiB; inspect its byte length and initial preview.
- Enter a decimal or 0x offset in the navigation field to inspect another 256-byte window.
- Select insert, replace or delete, enter the edit offset and required byte count and hex payload, then apply.
- Review the updated hex/ASCII bytes and active change log; use Undo if needed.
- Download the edited binary and its JSON change report with SHA-256 hashes.
Use cases
- Patch a known byte in a small test fixture without opening a desktop hex editor
- Compare header bytes before and after a manual binary experiment
- Remove a short byte range from a local sample and document the exact edit
- Prepare a reproducible offset-and-hash report for a teammate
Frequently asked questions
Does this change the file on my device?
No. The browser reads the selected file and edits a separate in-memory copy. Downloading saves a new file with .edited before its extension; the original is never overwritten by this tool.
How do offsets and replacement lengths work?
Offsets are zero-based decimal numbers or 0x hexadecimal numbers. Insert allows the position at end of file. Replace and delete require a positive byte count that fits inside the current copy. A replacement may have a different number of bytes than the removed range.
What hex syntax is accepted?
Enter complete byte pairs such as DE AD or DEADBEEF. Spaces, colons, commas, underscores and hyphens may separate groups; each group can begin with lowercase 0x. Odd digits and non-hex characters are rejected.
What are the limits?
Input and edited output are each limited to 8 MiB. Each edit may remove or insert at most 64 KiB, and up to 50 active edits can be undone. Only 256 bytes are rendered per preview page to keep navigation responsive.
What does the change report prove?
It records the current edit sequence, removed and inserted bytes, sizes, and SHA-256 hashes of the original and edited copies. A hash helps identify exact bytes but does not authenticate the file or make a patch safe to run.
Privacy
The file is read only through the browser File API and stays in this tab. Editing creates a separate memory copy; the original file is never overwritten or sent to this site or analytics. Downloads start only when you choose them.
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