A few things worth knowing
Does this understand programming languages?
No. This is a text comparison of source code, not an AST, syntax, semantic or runtime comparison. It works with text from JavaScript, HTML, CSS, JSON and other languages without parsing or executing them. Moving a block can appear as removal and addition. There is no syntax highlighting or merge operation.
How are whitespace and line endings compared?
Spacing, indentation, tabs and the final line break participate in comparison. CRLF and CR normalize to LF before comparison, so line-ending convention changes alone are not differences. Line mode shows original/revised line numbers, a return marker for lines ending in LF and an explicit marker for a final line without a break. Tabs display at four-column stops but remain tab characters in the report.
Should I ignore letter case?
Usually keep this off for code because case changes can be meaningful. If enabled, the tool compares lowercase text and distinguishes a case-insensitive match from identical input. Unchanged segments display the revised spelling. This option does not establish equivalent program behavior.
What does word mode compare?
It compares Unicode word segments including punctuation and whitespace, not programming-language tokens. Segmentation uses Intl.Segmenter when available, with an explicit fallback. Use line mode for longer code snippets; dense code can reach the word-segment limit quickly.
What are the limits?
Each side accepts up to 100,000 UTF-16 units and 2,000 comparison segments. Inputs are never truncated. Word mode counts punctuation and whitespace segments as well as words. The longest-common-subsequence comparison is bounded to keep memory and work manageable. Editing an input or option clears old results and exports.
Is the downloaded report a patch file?
No. It is a readable TXT comparison report containing your code with JSON-escaped tabs and line breaks. It cannot be applied by git apply or patch. Review it before sharing because it contains source text. Copy/download are optional and nothing is stored by the tool.