Text diff checker
Compare two texts and highlight the differences.
FreeRuns in your browserNo signupUpdated 2026-10-29
Nothing leaves your browser. Paste configs, contracts or copy decks freely.
Added
+0
lines only in the changed text
Removed
−0
lines only in the original
Differences
About this tool
How it works and how to read the result.
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Web app & SaaS development
SaaS products and web apps, from first version to scale.
See the serviceWhat it does
A diff checker compares two versions of a text and shows exactly where they differ. Paste the original on one side and the changed version on the other; additions are marked in green, removals in red with a strike-through, and unchanged text stays plain. You can compare whole lines, which suits code and configuration, or individual words and characters, which suits copy and translations. A unified patch is generated at the same time for anyone who needs a machine-readable record of the change.
How to use it
- Paste the original text in the first box and the newer version in the second.
- Choose how to compare. Lines for code and config, words for sentences, characters for small edits.
- Tick "Ignore whitespace" when indentation changed but content did not, or "Ignore case" for text where capitalisation is not meaningful.
- Read the highlighted view, then copy the patch if someone else needs to apply the change.
How to read the result
The two stats summarise the change. In the sample nginx config, the result shows +5 lines added and −4 removed. Reading the highlights, you see that "listen 80" was replaced by "listen 443 ssl", a second server name was added, index.htm joined the index list, the fallback changed from a 404 to the app's index.html, and a gzip directive was introduced.
A line that changed slightly appears as one red line followed by one green line, because line mode sees the old and new lines as different units. Switch to word mode to see which specific words changed inside that line.
When nothing is highlighted and the panel title reads "No differences", the texts are identical under the options you chose. Switching off "Ignore whitespace" may then reveal tab-versus-space differences that are invisible at a glance but matter to YAML and Makefiles.
Diffs like this are how we review configuration changes before deploying a web app. If the files you compare are JSON, tidy both with the JSON formatter first so the diff shows real changes rather than formatting noise.
Questions
Frequently asked.
What is the difference between line, word and character mode?
Line mode treats each line as one unit and is best for code and config files. Word mode highlights the changed words inside a sentence and suits prose or marketing copy. Character mode shows single-character edits such as a changed digit or a typo, which can be noisy on long texts.
Is it safe to paste contracts or credentials?
Yes. The comparison runs in your browser with JavaScript, and nothing is sent to a server. You can check this by loading the page, switching off your network connection and pasting the texts; the diff still works. Close the tab when you are done and nothing remains.
What is the patch output for?
It is a unified diff, the same format git and the patch command use. You can save it and apply it with "git apply" or "patch -p0", attach it to a ticket so a developer sees exactly what changed, or paste it into a code review as a precise description of the edit.
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