5 checks
Leading-line insertion
Reconstructs both versions and verifies 1 added, 0 removed, 3 unchanged.
Repeat text with a preset or custom separator while checking the exact UTF-8 output size before constructing a potentially excessive preview.
Up to 10,000 repeats and 1 MB of UTF-8 output
Type or paste the text you want to repeat. It can be a word, sentence, paragraph, symbol, or any string — including special characters and whitespace.
Choose how many times to repeat and pick a separator: newline, space, comma, or a custom string. The separator is inserted between each repetition, not at the end.
Inspect the exact UTF-8 byte count, then copy the result. Output above 1,000,000 bytes is rejected before construction to keep the browser preview bounded.
| Separator | Result format | Best for |
|---|---|---|
| None | abcabcabc | Concatenated strings, pattern art |
| Space | abc abc abc | Word lists, natural language repetition |
| Newline | abc↵abc↵abc | Line-by-line lists, CSV rows, multi-line output |
| Comma | abc,abc,abc | CSV values, array literals, SQL IN clauses |
| Comma + space | abc, abc, abc | Readable comma-separated lists |
| Custom | abc | abc | abc | Pipe-delimited tables, any custom delimiter |
The tool first calculates textBytes × repeats + separatorBytes × (repeats − 1). It constructs the result only when that value is at most 1,000,000 UTF-8 bytes. This is a browser-preview safeguard, not a claim that one megabyte is suitable for every downstream application.
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
Compare text differences
Merge multiple PDF files into one
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