Free Online Text Diff Checker — Compare Text & Code Differences

Overview: Find Differences Between Two Texts with Side-by-Side Diff

Compare two texts or source code snippets side-by-side with line and character diff highlighting. All computations and data processing are executed 100% locally on your device using client-side WebAssembly, HTML5 Canvas, and modern Web APIs without uploading files to any external server.

Supported Formats

Text & Code Diff Checker supports the following file formats:

  • .txt — client-side processing support.
  • .js — client-side processing support.
  • .json — client-side processing support.
  • .html — client-side processing support.
  • .css — client-side processing support.

How to Use Text & Code Diff Checker in Browser

  1. Paste Original: Enter original text in the left pane.
  2. Paste Modified: Enter updated text in the right pane.
  3. Inspect Diff: View line-by-line additions, deletions, and unified patch with stats.

Key Features & Privacy Protections

  • 100% Client-Side Privacy: Zero cloud upload. Your documents, photos, and files never leave your local browser sandbox.
  • Zero Installation: Runs instantly in Chrome, Safari, Firefox, Edge, Android, and iOS browsers.
  • Free Forever: No sign-up, no subscriptions, no ads, and no file size limits.

Frequently Asked Questions (FAQ)

What algorithm is used to compute differences?

It uses the Myers Longest Common Subsequence (LCS) algorithm to accurately pinpoint exact line-level additions, deletions, and modifications.

Can I view differences in both Unified and Split views?

Yes, switch between 'Unified' (single column with +/- prefixes like git diff) and 'Split' (side-by-side columns).

Is confidential code safe to compare here?

Yes! Computation happens entirely inside your browser's JavaScript engine. No code or text is ever sent over the network.

Can I export or copy the diff report?

Yes, click 'Copy Diff Patch' to copy the complete git-style diff report directly to your clipboard.

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Text & Code Diff Checker

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v1.0.0Free · Myers LCSText & Writing Tools

Free Online Text Diff Checker — Compare Text & Code Differences

Find Differences Between Two Texts with Side-by-Side Diff. Compare two texts or source code snippets side-by-side with line and character diff highlighting.

What is Diff Checker and what does it do?

The Text & Code Diff Checker is a visual text comparison tool that analyzes two text blocks, source code files, or document versions to identify insertions, deletions, and line-by-line modifications with precision.

With support for both side-by-side split and unified inline views, as well as character-level difference highlighting, it allows engineers, editors, and legal professionals to inspect changes without risking data exposure on third-party servers.

  • Detect line additions, deletions, and intra-line word-level or character-level modifications.
  • Dual view modes: side-by-side split comparison for wide displays and unified inline diff for compact review.
  • Options to ignore whitespace differences and toggle case sensitivity for code and config auditing.
  • Summary statistics reporting total added lines, removed lines, modified blocks, and change percentage.
  • 100% client-side diffing using Myers-algorithm-based diff engines with zero server logging.

How does Diff Checker work?

The diff algorithm computes the Longest Common Subsequence (LCS) between the original and modified strings, generating an optimal edit script representing additions and deletions.

Intra-line differences are calculated for modified blocks to highlight specific changed tokens. The resulting diff tree is rendered with color-coded syntax markers for immediate visual comprehension.

100% private: all processing happens locally in your browser using client-side WebAssembly, HTML5 Canvas, and modern Web APIs. Your files are never uploaded to any server.

Who needs Diff Checker?

Software Engineers & Code Reviewers

Compare configuration files, JSON payloads, SQL scripts, and code snippets outside of git command-line environments.

Legal Professionals & Contract Managers

Pinpoint subtle wording changes, clause additions, or omitted provisions between competing contract drafts.

Editors & Copywriters

Review editorial revisions, proofread student submissions, and verify changes made across article revisions.

System Administrators & DevOps

Audit differences between environment variables, nginx configs, Dockerfiles, and server configuration files.

Supported file formats

Text & Code Diff Checker processes the following file extensions and data formats directly in your browser:

.txt.js.json.html.css

How to use Diff Checker — step by step

  1. 1

    Paste Original

    Enter original text in the left pane.

  2. 2

    Paste Modified

    Enter updated text in the right pane.

  3. 3

    Inspect Diff

    View line-by-line additions, deletions, and unified patch with stats.

Frequently asked questions

What algorithm is used to compute differences?

It uses the Myers Longest Common Subsequence (LCS) algorithm to accurately pinpoint exact line-level additions, deletions, and modifications.

Can I view differences in both Unified and Split views?

Yes, switch between 'Unified' (single column with +/- prefixes like git diff) and 'Split' (side-by-side columns).

Is confidential code safe to compare here?

Yes! Computation happens entirely inside your browser's JavaScript engine. No code or text is ever sent over the network.

Can I export or copy the diff report?

Yes, click 'Copy Diff Patch' to copy the complete git-style diff report directly to your clipboard.

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