Text Diff/Compare Tool
Compare two texts and highlight differences with various comparison modes. Shows additions, deletions, and changes with visual highlighting, statistics, and export options.
Original Text
Characters: 0 • Words: 0 • Lines: 1
Try Sample Comparisons
Modified Text
Characters: 0 • Words: 0 • Lines: 1
Comparison Results
Enter texts to see comparison
How to use the tool
Paste the original text into the left input area
Paste the modified text into the right input area
Choose comparison mode (line-by-line or character-by-character)
View the side-by-side diff with additions, deletions, and unchanged content highlighted
Review the statistics: lines added, removed, modified, and similarity percentage
Copy the diff result or export as HTML for sharing
Frequently Asked Questions
How do I compare two texts and see their differences?
Paste two text inputs side by side. The tool computes the diff, showing additions, deletions, and unchanged segments. Output: synchronized side-by-side view, inline diff view, and statistics (lines added/removed/modified, similarity percentage). Runs entirely in your browser — your text never leaves the device. Useful for: document version comparison, code review, finding edits between drafts.
What's the difference between this and Text Diff?
Both compare text. [Text Diff](/tools/text-diff/) is the standard side-by-side comparison. This Text Diff Compare Tool may offer additional features like similarity percentage, summary statistics, or different display modes — depending on the specific implementation. For most use cases, either works; pick based on the UI/features you prefer.
Is my text sent to a server?
No — comparison runs entirely in your browser via JavaScript diff algorithms (typically a variant of Myers' diff or Wu-Manber). Your text never reaches a server, never gets logged. Verify in DevTools' Network tab: zero HTTP requests during comparison. Safe for comparing sensitive document versions.
What does the similarity percentage mean?
Similarity percentage estimates how much of the two texts is shared. Calculated typically as: (length of unchanged content) / (max length of either input) × 100. 100% = identical; 0% = completely different. Useful for: plagiarism-checking proxies, content-similarity analysis, version-comparison summaries. Limitations: based on text overlap, not semantic similarity — 'cat' and 'feline' have 0% text similarity but identical meaning. For semantic similarity, use NLP-based tools.
How does the diff algorithm work?
Most diff tools use a variant of Eugene Myers' 1986 diff algorithm or its successors. The algorithm finds the longest common subsequence (LCS) — the maximum amount of shared content — between the two inputs. Anything not in the LCS is an addition (in second only) or deletion (in first only). Modern implementations optimize for typical text changes (line-level for code, word-level for prose). The result is the minimum edit script transforming the first text into the second.
Can I compare code or structured data?
Yes — text-based diff works on any text. For code review, the line-level diff is standard. For JSON or XML, format-specific diff tools are better (use [JSON Diff](/tools/json-diff/) for JSON — it understands object/array semantics). For binary file comparison, this tool doesn't help — use specialized binary-diff tools. For most ad-hoc comparison of text content (documents, code, logs, configuration), this tool is the right choice.
How large can the texts be?
Browser performance limit. Up to ~1-2 MB per side compares quickly. Past 5 MB, performance degrades (diff is O(n×m) in basic implementations). For very large texts, use Unix `diff` or git's diff tooling. For comparing multiple files at once, use Beyond Compare, Meld, or your IDE's diff view. This tool fits the common case of comparing documents, code snippets, or text up to a few thousand lines.
Can I export the diff result?
Most tools allow copying the diff view or saving as HTML for sharing. For programmatic diff (unified diff format used by `diff -u` and Git), command-line tools are better. For visual diff review and sharing screenshots with annotations, this tool's side-by-side view works well — capture the screen as needed. For code review, use Git pull requests with built-in diff views, which support inline commenting.
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