What Is This Tool?
A diff (difference) tool compares two texts and shows the minimal set of changes that turns one into the other. It's how version control systems like Git display code changes, and it's equally useful for comparing configuration files, contracts, articles or any two versions of anything.
This tool diffs line by line using the same underlying algorithm family (longest common subsequence) as classic diff utilities, so the output reads like a familiar code review: + for added lines, − for removed lines.
Why Use It?
- See what actually changed between two versions instead of eyeballing them.
- Familiar git-style output: green additions, red deletions, context lines between.
- Summary count of added and removed lines at a glance.
- Works with any text — code, configs, documents, lists.
- Private: both texts stay in your browser, nothing is uploaded.
How to Use
- Paste the original text in the left box.
- Paste the changed version in the right box.
- Click "Compare".
- Read the result: green lines were added, red lines were removed, plain lines are unchanged.
Example
Input
Original:
line one
line two
line three
Changed:
line one
line 2
line threeOutput
line one
− line two
+ line 2
line threeThe middle line was changed, which the diff shows as removing the old line and adding the new one.
Frequently Asked Questions
Does it compare word by word or line by line?
Line by line, like git diff. A changed line appears as one removal plus one addition. Line-level diffs are the standard for code and configs and stay readable for large texts.
Why does a tiny change show the whole line as changed?
Because the unit of comparison is the line — any change within it marks the whole line. Split long paragraphs into shorter lines if you need finer granularity.
Does whitespace matter?
Yes. Lines must match exactly, so a trailing space or different indentation makes lines count as different. This is intentional — whitespace differences are real differences in code and configs.
Is there a size limit?
No hard limit, but very large texts (tens of thousands of lines) may take a moment since the comparison runs locally on your device.
Are my texts uploaded for comparison?
No. The diff algorithm runs entirely in your browser with JavaScript. Both texts stay on your device — safe for contracts, internal docs and unreleased code.