Text Diff Checker
Compare two blocks of text line by line and see what was added, removed, or unchanged.
Every comparison runs locally in your browser. Nothing you paste here is sent to a server.
+2 added · −1 removed
The quick brown fox- jumps over the lazy dog+ jumps over the sleepy dog+ A new final line.The end.
For informational and educational purposes only — not professional or technical advice, and not a substitute for consulting a qualified professional about your specific situation. TrueMeasureKit is not liable for decisions made based on these results. See our Terms of Service.
How this finds the smallest set of changes
Rather than comparing line-by-line positionally, this uses the longest common subsequence (LCS) algorithm — the same family of algorithm behind git diff. It finds the longest run of lines that appear in the same relative order in both versions, then marks everything else as added or removed around that skeleton. That's why inserting a line near the top doesn't cause every line below it to show as changed — only the lines that actually differ are flagged.
Frequently asked questions
How does line-by-line diffing decide what changed?
It compares both texts line by line and finds the longest common subsequence, then marks anything outside that shared sequence as added or removed — the same general approach source control diff tools use.