Who this helps
- People reviewing edits to a draft, configuration or log sample.
- People comparing line-based text before copying a report.
Developer Utility
Text Diff Checker
Compare two texts to check added, removed, and unchanged lines. Useful for reviewing differences in sentences, code, configuration files, and notices before and after edits.
Line-based comparison
Compare original and changed text line by line to find differences.
Change classification
Separate added, removed, and unchanged lines to understand the edit flow.
Copy and download
Copy comparison results or save them as a report file for sharing.
Text input
Enter the original text and changed text to compare.
Line-based comparison
Useful for checking line-level changes in sentences, code, and configuration files.
Compare options
Ignore spaces, blank lines, or case differences to focus on actual content changes.
Comparison result
Check added, removed, and unchanged lines with colors and symbols.
0
Added
0
Removed
0
Same
0
Total
Enter two texts and click the compare button.
How text comparison works
Results are classified line by line, making it easy to review document edits or code changes.
Added lines
Lines newly added in the changed text. Useful for checking new sentences, code, or settings.
Removed lines
Lines that existed in the original text but disappeared from the changed text.
Unchanged lines
Lines that exist identically in both texts, helping you see what stayed the same.
Compare text by lines without mistaking an insertion for a rewrite
The tool aligns matching lines, then marks additions and deletions. A line inserted in the middle does not have to make every later line look changed. Use the options carefully: ignoring differences also hides information.
When to use this tool
- Find a newly added setting in a short configuration.
- Compare two drafts while optionally ignoring capitalization or outer whitespace.
From input to a checked result
- 1
Paste nonempty text into both inputs. Each side supports up to 200,000 UTF-16 units and 1,500 comparison lines.
- 2
Choose whether to ignore leading/trailing whitespace, blank lines or letter case.
- 3
Run the comparison and read = for matching lines, - for removed lines and + for added lines.
- 4
Check the source context before interpreting the change percentage.
- 5
Copy or download a text report. Recompare after changing the inputs or options.
Insert a line
- Input
- Original: A\nB\nC Changed: A\nNEW\nB\nC
- Result
- 3 matching lines, 1 added, 0 removed; change rate 25%.
The denominator is the 4 aligned output rows, not the number of characters.
Ignore case and outer whitespace
- Input
- Original: Status: OK Changed: status: ok Enable both ignore-case and ignore-space options
- Result
- 1 matching line, no additions or deletions.
These are comparison rules. Internal spaces still matter; use the original text to review exact formatting.
How it works
CRLF line endings are normalized to LF. Selected options build comparison lines, and a longest common subsequence aligns them. A changed line is represented as a deletion and an addition. Change rate is rounded from (added + removed) / (same + added + removed) × 100.
Limitations
- This is a line comparison, not a word-level or semantic comparison.
- Repeated identical lines may have more than one valid alignment.
- A moved block can appear as deleted and added; there is no separate move detection.
- Both inputs must contain text. The tool does not compare a completely empty file with a populated one.
Your data
The text and report are processed in the browser rather than sent to the win-j server. Review what you copy into a report before sharing it.
References
Related tools
- Text Cleanup Tool
Remove unwanted hard line breaks before comparing drafts.
- Text Counter
Check the length of the final text after reviewing changes.
Frequently asked questions
Does a 25% change rate mean 25% of characters changed?
No. It counts added and removed rows as a fraction of all aligned output rows. Even one edited word can make an entire line appear twice: once removed and once added.
Does ignoring spaces remove every space?
No. It trims the start and end of each line. Different spaces between words remain differences.
Why is a moved line shown as deletion plus addition?
The alignment does not separately identify moves. Read both markers together with the surrounding lines.
Can I compare an empty document?
Both sides need non-whitespace text. Use a file comparison tool for additions to or deletions of an entirely empty file.