Text Diff Checker & Code Difference Viewer

Compare two code snippets or text documents line by line. Highlights added (+), removed (-), and unchanged lines with similarity scoring.

Text Comparison Inputs

Comparison Overview
56% Similar

Added

+6

Removed

-2

Same

5

Total Lines

13

Unified Diff View13 lines evaluated
function calculateTotal(items) {
let total = 0;
- for (let i = 0; i < items.length; i++) {
+ for (const item of items) {
- total += items[i].price;
+ total += item.price;
}
return total;
}
+⏎
+function formatCurrency(amount) {
+ return "$" + amount.toFixed(2);
+}

Zero Server Upload Privacy

Proprietary source code and documents are evaluated entirely inside client memory.

Myers Diff Algorithm & Sequence Similarity Formulations

Text difference engines compute the Longest Common Subsequence (LCS) to minimize edit distance:

1. Sequence Similarity Metric Equation
Similarity S(A, B) =
2 × |LCS(A, B)||A| + |B|
× 100%
2. LCS Dynamic Programming Recurrence
LCS(X_i, Y_j) = (x_i = y_j ? LCS(X_{i-1}, Y_{j-1}) + 1 : max(LCS(X_{i-1}, Y_j), LCS(X_i, Y_{j-1})))
Step-by-Step Diff Computation & Alignment Breakdown
Step 1: Line Array Tokenization
Split text streams A and B into discrete line arrays.
Step 2: Line Alignment & Delta Identification
Match lines sequentially and tag mismatches as additions (+) or removals (-).
Step 3: Unified Visual Patch Rendering
Visual Diff=Color-Coded Additions & Deletions

Diff Markers & Unified Patch Format Reference

SymbolDiff ClassificationColor HighlightMeaning
+AdditionGreen BackgroundNew line introduced in revised version
-DeletionRed StrikethroughOriginal line removed or altered
UnchangedNeutral GrayLine is identical in both versions

Frequently Asked Questions

How does the diff checker compare two texts?
The diff checker compares two texts line by line. Identical lines are marked as unchanged (gray), deleted lines are shown with strikethrough red highlights (-), and newly introduced lines are highlighted in green (+).
What types of files and formats can I compare?
You can compare source code files (JavaScript, TypeScript, Python, Go, Rust), structured configs (JSON, YAML, ENV), markdown articles, CSV files, and plain text documents.
Is my code or document data sent to external servers?
No. All text tokenization and diff calculations execute 100% locally inside your browser memory using client-side JavaScript. No confidential intellectual property is transmitted.
What algorithm does this diff viewer use?
The engine calculates line-level alignments and delta sets inspired by the Myers diff algorithm and Longest Common Subsequence (LCS) theory.

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