How to use Diff checker
- Paste the original text on the left and the changed text on the right.
- Compare by lines for code and lists, words for prose, or characters for short strings.
- Read the counts and the highlighted differences, which update as you type.
- For line comparisons, copy the result as a unified diff.
Lines, words or characters
Compare by lines for code, configuration files, lists and logs: each changed line shows as removed and added, the way a code review does. Compare by words for prose such as contracts, policies and articles, where a reworded sentence should show only the words that changed rather than the whole paragraph. Compare by characters for short values such as IDs, keys and URLs, where a single swapped character matters.
Additions are highlighted in green and removals in red and struck through, and a summary counts them in the unit you chose. For line comparisons, Copy as unified diff gives you the result with + and - markers, ready to paste into a ticket, a chat or a code review comment.
How differences are found
The comparison uses jsdiff, an open-source implementation of Myers' algorithm, the same approach git uses. It finds the smallest set of insertions and deletions that turns the original into the changed text, which keeps the result readable: an inserted paragraph shows as one addition, not as every following line changing.
Ignore case treats capital and small letters as the same. Ignore leading and trailing spaces skips changes in indentation and trailing whitespace, which is useful when one version was reformatted.
Private by design
The texts you compare are often the sensitive kind: two versions of a contract, a configuration with secrets in it, or code that isn't public yet. Both stay in this browser tab. The comparison runs as you type, nothing is uploaded, and nothing is saved, so closing the tab clears it.
Common uses
Checking what changed between two drafts of an agreement, comparing an environment's configuration with production's, spotting the edit in a reworded policy, or confirming two exported files are identical before deleting one.
Limits
Very large texts, such as two logs of several megabytes each, take longer to compare by characters; compare those by lines. Binary files such as Word documents or images can't be compared as text, so export them to plain text first.
Questions
- Is my text uploaded?
- No. The comparison runs in your browser as you type, and nothing is saved. That matters when comparing contracts, configs or code.
- Can it ignore case or extra spaces?
- Yes. Ignore case treats A and a as the same; Ignore leading and trailing spaces skips differences in indentation and trailing whitespace.
- How does it decide what changed?
- It uses jsdiff, an implementation of Myers' algorithm, the same approach as git diff: it finds the smallest set of additions and deletions that turns one text into the other.