Text Diff/Compare Tool
Compare two texts and highlight differences in character, word, or line mode. Shows additions, deletions, and changes with visual highlighting, statistics, and a copy option.
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 (character, word, or line) and, optionally, ignore case or whitespace
View the inline diff, where additions, deletions, and changes are highlighted in one combined view
Review the statistics: total changes, additions, deletions, changes, unchanged items, and similarity percentage
Copy the diff result as text
Frequently Asked Questions
How do I compare two texts and see their differences?
Paste the original and modified texts into the two input panels. The tool computes the diff, showing additions, deletions, changes, and unchanged segments in a single inline view below the inputs (there is no side-by-side view), plus statistics (total changes, additions, deletions, changes, unchanged, 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. This Text Diff Compare Tool offers character, word, and line comparison modes, ignore-case and ignore-whitespace options, a similarity percentage, and summary statistics, shown in an inline view. [Text Diff](/tools/text-diff/) is a separate tool; try both and pick the one whose display and options suit you.
Is my text sent to a server?
No — comparison runs entirely in your browser via a JavaScript implementation of Myers' diff algorithm. 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 as: (number of unchanged items) / (the larger item count of the two inputs) × 100, where an item is a character, word, or line depending on the mode. 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. It cannot measure semantic similarity.
How does the diff algorithm work?
This tool uses a variant of Eugene Myers' 1986 diff algorithm. 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). The tool compares by character, word, or line depending on the mode you choose (line level suits code, word level suits prose). For very different texts, when the edit distance passes 3,000 items, the differing middle section is shown as one block of deletions and one block of additions instead of a detailed diff.
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?
It runs in your browser, so very large inputs slow down, especially in character mode, and the diff is recomputed as you type. The tool does not enforce a size limit and has not been tuned for megabyte-sized inputs. For very large texts, use Unix `diff` or git's diff tooling. 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?
You can copy the diff output as text with the Copy Diff button. There is no HTML or file export. For programmatic diff (unified diff format used by `diff -u` and Git), command-line tools are better. For sharing, take a screenshot of the highlighted inline view. For code review, use Git pull requests with built-in diff views, which support inline commenting.
Share This Tool
Found this tool helpful? Share it with others who might benefit from it!
💡 Help others discover useful tools! Sharing helps us keep these tools free and accessible to everyone.