Text Diff Checker Online — Free
Runs 100% in your browser — your files never leave your device.
A full code editor is overkill when you only need to see what changed between two drafts, configuration snippets, or lists. Paste the original and revised text side by side; removed lines appear red and struck through, while added lines appear green.
How it works
- 1
Paste the original text
Put the earlier version in the left panel.
- 2
Paste the changed text
Put the revised version in the right panel.
- 3
Review the highlights
Red lines were removed; green lines were added.
About this tool
How the comparison works
Paste the original and the changed version, and the tool aligns them line by line, marking exactly what was added, removed, and left alone. The algorithm finds the true minimal edit — moved text shows as paired changes, not noise.
When you need a diff
Review what a find-and-replace pass actually changed, compare two versions of a config before deploying, check a colleague's edit against the original, or verify that a cleanup removed what it claimed and nothing else.
Reading a diff efficiently
Read the removals first — what disappeared is usually the story. Then scan additions for surprises. Identical lines collapse out of the way, so a 500-line document with three changes shows you three changes, not 500 lines.
Frequently asked questions
How large a text can it compare?
Documents of thousands of lines compare instantly in your browser. Everything runs locally — sensitive configs and contracts never leave your device.
Does the diff work word-by-word or line-by-line?
Line-by-line — whole lines are the unit of comparison, which keeps results stable and readable even when punctuation shifts inside a line.
Is my text uploaded anywhere?
No — comparison runs entirely in your browser. Both versions stay on your device.