Diff Checker: Compare Two Texts and Spot Every Difference Instantly
Paste two versions of any text and see additions, deletions, and changes highlighted line by line. Works for code, contracts, config files, or any text comparison.
Introduction
You updated a config file but now the app is broken. Which line changed? You received a revised contract and want to see exactly what the other party modified. Our Diff Checker takes two blocks of text, compares them character by character, and highlights every difference. Added lines show in green, deleted lines in red, and unchanged lines in neutral gray. It works for any text: source code, JSON configs, legal documents, essays, CSV data.
Step-by-Step Guide
Paste the original text
Put your original (or "before") version in the left panel. This could be a previous version of your code, the original contract, or any text you want to use as the baseline.
Paste the modified text
Put the updated (or "after") version in the right panel. The tool compares these two inputs to determine what has changed.
Review the diff
Click Compare and the output shows a unified or side-by-side diff. Green highlighted lines are additions in the modified version. Red highlighted lines are deletions from the original. White lines are unchanged.
Pro Tips & Best Practices
Before comparing minified code (like bundled JS or CSS), run both through a formatter first. Otherwise every line shows as "changed" because the whitespace is different, even if the actual logic is identical.
For large documents, use the "jump to next change" feature to skip past unchanged sections. Scrolling through 500 unchanged lines to find the 3 that differ is not a good use of your time.
This tool is great for reviewing changes before committing code. Paste your git diff or copy the before and after versions of a function.
Common Mistakes to Avoid
Frequently Asked Questions
Can I compare files directly instead of pasting text?
Currently the tool works with pasted text. To compare files, open both in a text editor, select all, copy, and paste each into the respective panel.
Does it support syntax highlighting for code diffs?
The diff output highlights changes (additions and deletions) but does not apply language-specific syntax highlighting. The focus is on showing what changed, not how the code is structured.
Is there a character or line limit?
There is no hard limit, but very large texts (over 100,000 lines) may slow down the comparison since the diffing algorithm runs in your browser. For most practical use cases, performance is instant.