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Compute similarity % and Levenshtein distance between strings. Use for fuzzy match scoring; for visual diff use text-diff-visual. Input: two strings ≤10MB. Returns similarity + distance. 100% client-side.
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Compares two strings and reports whether they are identical, shows the first point of difference, and calculates a similarity score using a Jaccard-style token overlap. Options cover case sensitivity, whitespace trimming, and line-by-line diff output.
Manually comparing strings — especially long generated values, config keys, or hash outputs — is tedious and error-prone. A comparator that pinpoints the exact difference and gives a numeric similarity makes quick work of the task.
This tool is part of the DevStackIO platform — a collection of free online developer tools from DevStackIO. Browse more free developer resources on DevStackIO.
Developers diffing config values or generated outputs, QA engineers verifying API responses, writers comparing document versions, and anyone validating that two values match.
Paste the first string into the left input
Paste the second string into the right input
Toggle case sensitivity and whitespace trimming as needed
Read the equality result, first-difference location, and similarity score
Switch to line-diff view to see added and removed lines
Re-run after normalizing whitespace if a false mismatch appears
'hello' vs 'hello' → Equal, similarity 100%'hello' vs 'hello!' → Different at index 5, similarity ~91%'ABC123' vs 'abc123' (case-insensitive) → EqualLine diff: line 2 removed, line 3 addedIs the comparison case-sensitive by default?
Yes, you can toggle it off for case-insensitive comparisons.
What does the similarity score mean?
It reflects token overlap on a 0-100 scale; higher means more shared content.
Does it handle Unicode?
Yes, it compares strings as text and highlights the differing position.
Is anything uploaded?
No, all comparison happens locally in your browser.
Authoritative specifications, standards, and in-depth reading for String Comparator.
Result
Equal
The similarity score is a token-overlap heuristic and is not a semantic guarantee. All comparison happens locally.
Obfuscate strings with masking and reversible transforms. Use when hiding PII in demos; for hashing use hash-generator. Input: text ≤10MB. Returns obfuscated text. 100% client-side.
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Count characters, words, lines, and bytes. Use for quick length checks; for full stats use word-counter. Input: text ≤10MB. Returns counts. 100% client-side.
Count words, characters, and sentences. Get reading time and Flesch score as you type.
Sort lines alphabetically and remove duplicates. Use when cleaning lists; for comparing two texts use text-diff-visual. Input: text lines ≤10MB. Returns sorted unique lines. 100% client-side.
Preview rendered Markdown without editing. Use for quick read-only preview; for editing use markdown-editor, for HTML output copy use markdown-to-html. Input: Markdown ≤10MB. Returns rendered HTML preview. 100% client-side.
Generate URL slugs from titles with lowercase rules. Use as default slug tool; slugify-string is a noindex alias. Input: text ≤10MB. Returns slug string. 100% client-side.
Visual side-by-side diff for two texts with char-level highlights. Use as default diff tool; for similarity score use string-comparison, for JSON use json-diff. Input: two texts ≤10MB. Returns visual diff. 100% client-side.