What does the Text Diff and Line Comparison do?
Use this tool when you need a browser utility that finds the longest common sequence of lines and marks insertions and removals. It accepts an original text and a changed text and returns a readable line diff with plus and minus markers. Results are deterministic for the same input except where cryptographic randomness, current time, or a live provider response is part of the task.
Line diff favors readable revisions
Use this page for configuration files, lists, and prose already divided into meaningful lines. Use JSON Diff for parsed JSON semantics or a word-level review tool for dense paragraphs.
How do you use it?
- Paste the earlier text into Original text and the revision into Changed text.
- Enable Ignore whitespace only when leading, trailing, and repeated spaces should not create a change.
- Read the + and − lines, then copy the plain patch view if needed.
Worked example
Replace one complete line
Input
Original:
alpha
beta
Changed:
alpha
gammaOutput
alpha
+ gamma
- betaThis implementation finds a longest common sequence of complete lines; it does not highlight changed characters inside a line.
Common errors and fixes
| Symptom | Likely cause | Fix |
|---|---|---|
| One edited sentence appears as a removal plus an addition. | The current comparison unit is the complete line. | Break long prose into stable lines or use a word-level diff when character-level review is required. |
| The page stops a very large comparison. | More than four million line pairs would require unsafe browser memory for the comparison table. | Compare smaller sections or use a streaming command-line diff for large files. |
Important behavior of Text Diff
This release compares complete lines; a changed line appears as one removal and one addition.
Standards and implementation references
- GNU Diffutils manual (opens in a new tab)Provides an authoritative reference for line-oriented comparison concepts; this page does not claim GNU patch compatibility.
Frequently asked questions about Text Diff
Does the Text Diff upload my input?
No. Processing runs in the current browser tab, and the page does not send tool input to a KitLumi processing endpoint.
What input does the Text Diff accept?
It accepts an original text and a changed text. The workspace checks the input and reports malformed or unsupported values before it produces a result.
What does the Text Diff produce?
It produces a readable line diff with plus and minus markers. Copy and download controls appear when the output format supports them.
What limitation should I know?
This release compares complete lines; a changed line appears as one removal and one addition.
What changed?
Added Line-by-line diff, Whitespace normalization, Copyable patch view, Local comparison, responsive controls, explicit runtime disclosure, and tested browser output.