Compare two files byte by byte
Text diffs are everywhere; a usable binary diff in the browser is not. Two firmware dumps, two exports, two “identical” binaries — the map shows where they disagree in one glance.
- Runs entirely in your browser
- Works offline
- No upload
- No sign-up
- No watermark
Loading the tool…
How it works
- Drop file A and file B.
- Read the heatmap: green slices match, red ones differ.
- Click a slice to inspect the exact bytes side by side.
Why nothing is uploaded
Every operation on this page is done by code running inside your browser tab, using the same engine that renders web pages. The file is read from disk into your tab’s memory, transformed there, and written back out as a download. It is never sent anywhere — not to us, not to a third party.
Verify it yourself
- Open your browser’s developer tools (F12) and select the Network tab.
- Load your file and run the tool.
- The only requests you will see fetch the tool’s own code — and, for a few heavy tools, their open-source engine from a public CDN — plus one small page-view ping to loreatec.jp (page address and title, nothing more). None of them carry your file.
Frequently asked questions
What do the colours mean?
Each cell summarises a slice of the file: fully green means identical, and the shift towards red is the fraction of differing bytes. A thin red line in a green sea is a patched header; solid red from a point onward usually means an insertion shifted everything after it.
Why is there a 50 MB limit?
Byte-by-byte comparison holds both files in memory. Beyond ~50 MB a tab starts to gamble with crashes, and this site prefers refusing to freezing.
Does it detect insertions like a text diff?
No — it compares positions, not sequences. An insertion makes everything after it “different” even though it merely moved. That is the limit of positional comparison, and the heatmap pattern usually makes such shifts easy to recognise.