Diff Checker

Spot the difference.

Compare two texts. See what changed. On-device.

Original
Modified
Click Compare to see the diff
No upload
Works offline
No idea what's in your data

Need to diff thousands of files? The offline bundle handles batches with no size limit. $99 once.

Get Bundle →
// How it works

Three steps. Zero uploads.

01
Paste
Paste two texts side-by-side, or drop two files. They stay on your device.
02
Compare
fwip highlights every difference — line-level and word-level. Added, removed, and changed text is colour-coded.
03
Review
Scroll through the diff with line numbers. Nothing was ever uploaded.
// Why this is different

Your text never leaves your machine.

Most online diff tools send your text to a server for comparison. Your code and documents pass through systems you don't control.

fwip works differently. The diff engine runs entirely in your browser. Your text is read from your device, processed on your CPU, and the result is saved back to your device. No server is involved. We literally cannot see your file.

No server processing

Everything runs on your device using WebAssembly. Your file never touches a network.

No account required

Drop a file. Get a result. No sign-up, no email, no password.

No subscription

Free in the browser. $99 once for the offline bundle. That's it. Forever.

Works offline

The desktop version works with no internet connection at all.

// Questions

Frequently asked.

How do I compare two text files without uploading?▾
Paste both texts into fwip or drop two files. It highlights differences line-by-line and word-by-word entirely in your browser. Your text never leaves your device.
Does fwip show word-level differences?▾
Yes. fwip highlights both line-level and word-level changes. Added text is green, removed text is red, and unchanged text is dimmed.
Can I compare code files?▾
Yes. fwip handles any text format including JSON, HTML, CSS, JavaScript, Python, and plain text. Line numbers are shown for easy reference.
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Offline. No browser. No internet. No excuses.
$15
This tool
  • Diff Checker · offline
  • Batch processing
  • No file size limit
  • 3 devices · one payment
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Complete suite
  • All 200+ tools · offline
  • No file size limit
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One-time payment · 3 devices · Updates included · Mac + Windows + Linux