Text Diff

Free online tool. All processing is client-side. No signup needed.

How to Use the Text Diff

1. Enter your input values above
2. Results update automatically
3. Copy or download the output

What is a Text Diff?

A Text Diff (difference) tool compares two blocks of text and highlights exactly what changed — additions, deletions, and modifications — line by line and character by character. Diff tools are essential in software development for reviewing code changes (git diff), in legal and business for comparing contract versions, in content editing for tracking revisions, and in data analysis for spotting differences between datasets. The tool uses the Longest Common Subsequence (LCS) algorithm to compute the minimal set of changes needed to transform text A into text B.

How Does It Work?

Paste original text on the left and modified text on the right. The diff engine computes the differences using a character-level or line-level comparison algorithm. Results are displayed with color coding: red background for deleted text, green for added text, and unchanged text in white. Options include: line-by-line mode (good for code and structured text), word-by-word mode (good for prose and documents), and inline diff (changes shown within lines).

Formula

LCS Algorithm (Longest Common Subsequence):\nD[i,j] = 0 if i=0 or j=0\nD[i,j] = D[i−1,j−1] + 1 if A[i] = B[j]\nD[i,j] = max(D[i−1,j], D[i,j−1]) otherwise\n\nBacktrack from D[m,n] to find the diff:\n• Diagonal move = unchanged\n• Up move = deleted from A\n• Left move = added to B\n\nSimilarity = LCS Length ÷ max(len(A), len(B)) × 100%

Who Uses This Tool?

• Developers comparing code versions or reviewing pull requests
• Legal professionals comparing contract drafts and clause changes
• Content editors tracking document revisions and proofreading changes
• System administrators comparing configuration files between servers
• Students checking for plagiarism or verifying paraphrasing

Pro Tips

• For code diffs, use line-by-line mode with 'ignore whitespace' enabled — this filters out indentation-only changes
• For prose/text comparison, use word-level diff which produces cleaner results for paragraph-level changes
• Clear and structured input improves diff quality: remove extra blank lines and normalize spacing before comparing
• Our diff tool is client-side — your text never leaves your browser. For very large files (>1MB), consider using command-line diff tools instead

Frequently Asked Questions about Text Diff

What's the difference between character and line diff?

Line diff compares text line by line and is best for code, logs, and structured text. Character/word diff finds changes within lines and is better for prose, editorial changes, and paragraphs.

How is this different from git diff?

Git diff compares file versions tracked in git history and includes metadata (commit, author, line numbers). Our tool is a general-purpose text comparison for any two pieces of text, not tied to version control.

Free online Text Diff — no signup, 100% client-side processing. All data stays in your browser.