Text diff checker
Paste two versions of any text and see exactly what changed — line by line, word by word.
How to compare two texts online
Paste the first version of your text into the Original panel on the left and your revised version into the Modified panel on the right. The diff result appears immediately below — no button required. Added lines are highlighted green with a + prefix, removed lines are highlighted red with a - prefix, and modified lines show both the old and new version with the specific words that changed highlighted within each line.
Line-level and word-level differences
The diff checker compares text at two levels of detail. At the line level it identifies which lines were added, removed, or modified. When a line is modified rather than completely replaced, the tool also runs a word-level comparison on that specific line pair, highlighting exactly which words changed inside it. This makes it easy to spot a single word correction in a long paragraph without reading the whole line twice.
Who uses a text diff checker
Writers use the diff checker to compare draft versions of an essay or article and see what they or an editor changed. Developers use it to compare config files, documentation, or any text that is not in version control. Students use it to compare their submission against a revised or corrected version. Translators use it to track changes in the source document between review cycles. Anyone who has two versions of a text and wants to know exactly what is different will find it useful.
Reading the diff result
Each line in the result is prefixed with a symbol and colour. A green line starting with + is a line that exists only in the Modified version — it was added. A red line starting with - is a line that exists only in the Original version — it was removed. Lines without a prefix are unchanged and appear in both versions. When a line is modified, the old version appears as a red - line and the new version appears as a green + line directly below it, with the changed words highlighted in a stronger colour inside each line.
Frequently asked questions
How does the text diff checker work?
The tool uses a longest-common-subsequence algorithm to find the minimum set of changes needed to turn the original text into the modified text. Added lines appear green, removed lines appear red, and modified lines show word-level highlights. The result updates automatically as you type.
What does the diff checker highlight?
Added lines are highlighted green with a + prefix. Removed lines are highlighted red with a - prefix. Modified lines show both versions with the specific changed words highlighted in a darker shade so you can see exactly what was edited without reading the entire line.
Can I compare documents, essays or config files?
Yes. The tool works on any plain text — essays, emails, code, config files, JSON, CSV, Markdown or any other text format. Paste plain text for best results. The tool handles up to 3000 lines per side.
Is my text sent to a server?
No. All comparison happens entirely in your browser. Your text is never uploaded and never leaves your device. The tool works offline once the page is loaded.
How do I copy or save the diff result?
Click Copy diff above the result panel. This copies the diff in unified format — each line prefixed with + for additions and - for removals — ready to paste into a document, email or issue tracker.