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Text Diff Checker

Compare two text documents or code blocks to see line-by-line differences and character-level highlights.

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Compare two text blocks or source code documents side-by-side to highlight character-level insertions, deletions, and line differences client-side.

Learn About This Tool

Understanding Split vs Unified Diff Views

A diff tool displays differences between files.Split view aligns the original and modified texts in two adjacent columns, matching unchanged lines and showing blank filler rows where lines were added or removed.Unified view stacks the differences sequentially in a single column:
// Standard git-style unified diff representation:
- const oldVariable = "original value";
+ const newVariable = "modified value";
  • Use Split View to compare long code structures or column layouts side-by-side
  • Use Unified View for a compact, sequential git-style comparison history
  • Character highlights indicate specific word modifications inside lines
  • Compare configuration files or text edits quickly inside your browser

Character-Level Inline Diff Highlights

Standard diff utilities only check line-by-line changes. Our advanced client-side comparator runs a character-level Longest Common Subsequence (LCS) search on adjacent mismatching lines. This highlights the exact characters, letters, or punctuation that were modified, saving debugging time. If you are comparing encoded template documents, you can pre-format them with our HTML Entity Converter.
  • Removed characters are shaded in red within the original line block
  • Added characters are shaded in green within the modified line block
  • Unchanged parts of modified lines remain highlighted normally
  • Helps you spot single-character bugs, syntax typos, or missing commas

Privacy-Preserved Local Diff Verification

Many online tools send your private copy or code tokens to remote servers for diff generation. This tool runs entirely browser-native in client-side JavaScript. If you are comparing complex parameters or API configurations, pretty-print them first with our JSON Formatter.
  • 100% browser-native processing prevents server-side leaks
  • Safe for API keys, secret configs, and database connection strings
  • No logins, cookies, or trackable identifiers are required to compare
  • Instant computation speeds since there are no network request latency lags

How to Use Text Diff Checker

1

Input Text Blocks

Paste your original text in the left panel and your modified text in the right panel.

2

Configure Comparison Rules

Choose between Split and Unified views, and toggle Ignore Case or Ignore Whitespace options.

3

Inspect Differences

Review the color-coded report. Red highlights denote removals, and green highlights denote additions.

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Common questions

What is an LCS Diff algorithm?

LCS stands for Longest Common Subsequence. The algorithm finds the longest sequence of lines or characters common to both inputs and constructs the diff report by identifying elements outside this sequence.

Is my text data safe?

Yes, the comparison runs entirely client-side in your browser. None of the text or code is transmitted to any server.

How does 'Ignore Whitespace' work?

When enabled, the parser collapses multiple spaces into a single space and trims leading/trailing spaces before calculating differences. This is useful for formatting-insensitive code changes.

Can I compare code files using this tool?

Yes, you can copy-paste Javascript, JSON, HTML, Python, YAML, or any raw code formats to inspect syntax or parameter adjustments.

What do the line numbers in Split View represent?

The left column displays original line numbers, and the right column displays modified line numbers. Empty rows are aligned to preserve structure.

Why are some words highlighted inside a line?

If a line is replaced, the tool calculates character-level diffs within that specific line range to show you the exact words or symbols modified.

Does this tool support comparing entire files?

Yes. You can copy the contents of any files (like script.js, config.json, or article.txt) and paste them directly into the left and right inputs to compare them.

How are empty lines displayed in Split View?

To keep the original and modified lines aligned side-by-side, the tool inserts blank filler rows on the side that doesn't contain the line. These lines are colored in light gray with no line numbers.

Can I export the diff report?

You can copy individual segments or take a screenshot of the aligned diff layout. Since the tool operates client-side, the easiest way to share a report is by copying the modified output text directly.

How does the 'Ignore Case' option affect the diff?

When 'Ignore Case' is checked, characters like 'A' and 'a' are treated as identical. This helps you identify functional differences in text or code without being distracted by letter casing changes.

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