Online Hex Editor
View any file as a hex dump with offsets and ASCII, search for bytes or text, patch bytes at chosen offsets and download the edited file — all in your browser.
A hex editor shows the raw bytes of a file — every value from 00 to FF with its offset — so you can inspect headers, find magic numbers, check line endings or patch a value without any special software. This one opens any file locally in your browser, shows a classic offset / hex / ASCII view, searches for byte patterns or text, and saves a patched copy.
How to use this tool
- Drop the file into the box — it is read on your device and never uploaded.
- Set the start offset and how many bytes to view (up to 4 KB per page).
- Optionally search for hex bytes such as 50 4B 03 04 or for text.
- Type edits as offset: bytes, for example 0x1A: FF 00, or 200 = "OK", then download the edited file.
Formula
byte offset = row offset + column (0–F) · edit line: offset: hex bytes or offset = "text"
Offsets count from 0 and can be written in decimal (26) or hex (0x1A). Each row holds 16 bytes, so the row offset always ends in 0 in hex. Edits overwrite bytes in place: the file keeps exactly the same size, which is what patching binaries and fixing headers needs. Text in quotes is written as UTF-8. Quoted text uses JSON string escapes: \n writes a newline, and \" writes a quote.
Example
Open a 26-byte text file containing "Hello world.", a newline, "Second line." and another newline. File size shows 26 and the first row, 00000000, reads 48 65 6C 6C 6F 20 77 6F 72 6C 64 2E 0A 53 65 63. Enter the edit 0: 4A and H (48) becomes J (4A): Bytes changed is 1 and the downloaded copy starts "Jello world.". Searching for hex 0A finds 2 matches, at offsets 0x0C and 0x19 — the two line breaks.
Frequently asked questions
Is my file uploaded anywhere?
No. The file is read with your browser’s File API and the edited copy is built in memory, so nothing leaves your device.
Can I insert or delete bytes?
No — edits overwrite existing bytes, so offsets and the file size stay the same. Writing past the last byte is refused with a message instead of silently growing the file.
How big a file can it open?
The entire file and an edited copy must fit in browser memory; the practical limit depends on the device. The view shows up to 4 KB at a time. Search stops at 1,000 matches, and the search/change tables show the first 300 rows.
What do the dots in the Text column mean?
They stand for bytes that are not printable ASCII (below 20 or above 7E) — control codes, UTF-8 multi-byte parts or binary data.
Last updated: 2026-10-30