5 checks
Leading-line insertion
Reconstructs both versions and verifies 1 added, 0 removed, 3 unchanged.
Compare two text versions with line alignment that keeps later unchanged lines matched when content is inserted or removed.
0 UTF-16 code units · 0 lines
0 UTF-16 code units · 0 lines
Line-based alignment only. This tool does not measure plagiarism, authorship, or semantic similarity.
Paste the original or older version of your text into the left panel. This can be source code, a document, a config file, JSON, or any plain text.
Paste the newer or modified version into the right panel. The tool normalizes CRLF and CR line endings, then aligns exact lines before marking additions and removals.
Green rows are present only in the modified version, red rows only in the original, and grey rows match exactly. Copy the plain diff when you need a portable review note.
| Marker | Meaning | Display |
|---|---|---|
| + | Line or text added in the new version | Green highlight |
| - | Line or text removed from the original | Red highlight |
| − then + | A changed line appears as an exact removal followed by an addition | Red row, then green row |
| Unchanged line — identical in both versions | Grey row |
Controlled benchmark · September 15, 2026
Five owned fixtures exercise line alignment, Unicode-aware counting, separator placement, and the output-size guard. Every expected value and round-trip reconstruction matched.
5 checks
Reconstructs both versions and verifies 1 added, 0 removed, 3 unchanged.
5 checks
Reconstructs both versions and verifies 1 added, 2 removed, 2 unchanged.
6 checks
Checks words, grapheme clusters, non-whitespace graphemes, sentences, paragraphs, and lines.
3 checks
Checks exact output, repeat count, and UTF-8 byte size.
1 check
Verifies oversized repeated output is rejected before the string is constructed.
Boundary: this benchmark verifies these deterministic fixtures in the current JavaScript runtime. It does not prove semantic equivalence, plagiarism detection, identical counts across every locale, or suitability for arbitrarily large documents.
Character, word, and sentence segmentation follows the browser’s Intl.Segmenter behavior when available, which implements locale-sensitive segmentation defined by ECMA-402 and informed by Unicode text-boundary rules.
Count words and characters
Repeat text multiple times
Merge multiple PDF files into one
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