How to use the diff checker
- Paste the original text on the left and the changed text on the right.
- Click Compare.
- Green lines were added, red lines were removed.
About this tool
Paste the original on the left and the changed version on the right, then compare. Added lines show in green and removed lines in red. It is useful for config files, JSON responses, SQL, contracts and any text where you need to see exactly what changed.
How to read the result
The tool compares the two texts line by line and finds the longest run of lines they share. Lines only in the right-hand text are shown in green with a plus sign, and lines only in the left-hand text are shown in red with a minus sign. Unchanged lines have no colour. A line that was edited appears as one red line followed by one green line.
Useful things to compare
- Two versions of a config file, to see which setting changed.
- API responses before and after a deploy. Run both through the JSON formatter with Sort keys on first, so only real changes show.
- SQL queries, contract clauses, or a document before and after an edit.
- Two lists, to find the items missing from one of them.
Why everything shows as changed
The comparison is exact, so invisible differences count. Common causes are trailing spaces, tabs versus spaces, different line endings, and different indentation. Make both texts consistent first. For JSON, format both sides the same way. For plain lists, sort both sides with the Sort Lines tool.
Limits
Only the first 3,000 lines of each side are compared, which keeps the page fast. Changes inside a line are not highlighted word by word. For very large files, or for tracking changes over time, use a version control tool such as Git.
Frequently asked questions
Does it compare words or lines?
Lines. A changed line shows as one removed line and one added line.
Can I compare JSON?
Yes. Format both sides first with the JSON formatter so the structure lines up.
Is my text uploaded?
No. Everything runs in your browser. Nothing is uploaded.
Does it ignore whitespace?
No. Whitespace differences are treated as changes, so normalise both texts first if you want to ignore them.
Is my text uploaded?
No. The comparison runs in your browser and nothing is sent anywhere.