Developer tool · Free · No sign-up

Text & Code Diff Checker

Compare two blocks of text or code to find differences instantly.

Original Text

Modified Text

Differences

1Hello World

2This is line 2

3Line 3 is here

1Hello World

2This is line 2 modified

3Line 3 is here

4Line 4 is new

About this tool

Quickly compare two blocks of text or code to see exactly what changed. Whether you are comparing API responses, configuration files, or document drafts, this tool highlights added lines (green) and removed lines (red) side-by-side. Everything runs in your browser, so your code is never uploaded.

Key features

Side-by-Side View

Easily spot additions and deletions in a clean, color-coded layout.

Line-by-Line

Highlights exact line numbers and differences for precise debugging.

100% Private

Your text and code never leave your browser. No server-side storage.

How to use it

1Paste the original text/code into the left box.
2Paste the modified text/code into the right box.
3Click 'Compare' to see the highlighted differences.
4Use the 'Swap' button to reverse the comparison.

Common use cases

Checking what changed in a JSON API response.
Comparing two versions of a config file.
Reviewing text edits in a document.

Frequently asked questions

How does the diff algorithm work?

It uses a line-by-line comparison algorithm to detect which lines were added, removed, or kept the same, similar to Git's diff output.

Is my data sent to a server?

No. The comparison happens entirely in your browser's memory.

Can I compare large files?

Yes, it handles large text blocks easily, though performance may vary on extremely massive files.

Private and free. Most of our tools run entirely in your browser, so the data you enter isn't uploaded or stored. There's no sign-up, and there never will be — they're built by the Fusion Trail Solutions team to be genuinely useful.