Are my files uploaded anywhere?

No. The comparison runs entirely in your browser, so your text and files never leave your device.

What is the difference between split and unified view?

Split view shows the original and changed text side by side in two columns. Unified view combines them into a single column with plus and minus markers, like a code review diff.

Can I compare code and JSON?

Yes. It works with any plain text including code, JSON, CSV, YAML and configuration files, and highlights the exact words that changed.

Developer Tools

Diff Checker

Compare two texts and highlight the differences line by line.

Free browser toolRuns in your browserNo sign-up

Advanced comparison workspace

Compare, inspect and selectively merge text changes

Use split or unified views, choose word or character precision, ignore known noise and export a standard patch or standalone HTML report.

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similarity

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change blocks

Split

view

Original text0 lines · 0 chars

Changed text0 lines · 0 chars

Private by design. Input is processed inside this browser tab and is not sent to ToolsOnDuty.

About the Diff Checker

Paste or upload two versions of any text or code and instantly see what changed, with additions and removals highlighted line by line and word by word.

Switch between a side-by-side split view and a combined unified view, ignore whitespace or letter case, and jump between changes with previous and next.

Everything runs in your browser, so your files are never uploaded, making it safe for private code, configs and documents.

Key features

Side-by-side split view and unified view
Line and word level highlighting
Open a file or paste text directly
Ignore whitespace or case, jump between changes

How to use

1Paste or open a file in the Original and Changed boxes.
2Click Find difference to compare them.
3Use Previous and Next to move between changes.

Examples

Compare an edited sentence

Input: Original: The sky is blue. Changed: The sky is clear.

Output: blue shown as removed and clear shown as inserted

Switch between split and unified views or export the resulting patch.

Frequently asked questions

Are my files uploaded anywhere?: No. The comparison runs entirely in your browser, so your text and files never leave your device.
What is the difference between split and unified view?: Split view shows the original and changed text side by side in two columns. Unified view combines them into a single column with plus and minus markers, like a code review diff.
Can I compare code and JSON?: Yes. It works with any plain text including code, JSON, CSV, YAML and configuration files, and highlights the exact words that changed.

Open a related tool to prepare your files or refine the finished result.