Text Diff Checker
Compare two texts and instantly see every word that was added, removed, or changed.
Comparing JSON data? JSON Diff compares keys and values while ignoring formatting and object key order.
+2 -2
- The quick brown fox jumps over the lazy dog.
+ The quick brown fox leaps over the lazy dog.
- It was a sunny afternoon.
+ It was a sunny afternoon in June.
About Text Diff Checker
This Text Diff Checker compares two blocks of text line by line and highlights exactly what changed — lines only in the original are shown as removed, lines only in the new version are shown as added, and unchanged lines are shown as-is. When a single line is edited rather than fully replaced, the tool highlights the specific words that changed within that line, not just the whole line. Switch to the side-by-side view to see both versions in parallel columns, similar to a code review diff. It's useful for comparing document revisions, checking configuration file changes, reviewing edited articles, or spotting differences between two versions of code or data. Everything is computed locally in your browser using a standard longest-common-subsequence diff algorithm.
Frequently Asked Questions
The tool compares text line by line using a longest-common-subsequence (LCS) algorithm — the same class of algorithm used by tools like Git and diff — to find the minimal set of additions and removals between the two versions.
To keep comparisons fast in your browser, each text is limited to 3,000 lines. For larger files, consider comparing smaller sections at a time.
Both — lines are compared first, and when one line is edited into another (rather than fully removed or added), the tool runs a second word-level comparison on that pair and highlights just the changed words.
Unified shows one column with removed lines above added lines, like a standard diff/patch file. Side-by-side shows the original and changed text in two parallel columns, which some people find easier to scan.