Developer Tools
Text Diff
Compare two texts side-by-side or in unified format with line, word, and character-level highlighting.
Your files stay on your device - processed locally via WebAssembly, never uploaded
Options
Paste text into both panes above to see the diff - or .
All diffing runs entirely in your browser. Your text is never sent anywhere.
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Copy this code to add the Text Diff to your site for free. It runs entirely in your visitors' browsers - no API key, no usage limits.
<iframe src="https://optipix.art/embed/text-diff" width="100%" height="600" style="border:1px solid #e4e4e7;border-radius:8px;" title="Text Diff by OptiPix" loading="lazy"></iframe> <p style="font-size:12px">Free tool by <a href="https://optipix.art/text-diff">OptiPix Text Diff</a></p>
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About Text Diff
Last updated: June 2026
OptiPix Text Diff is a full-featured text comparison tool that instantly shows you what changed between two versions of any text. Paste your Original and Modified text into the two panes and get a detailed diff in milliseconds. Choose between Side-by-Side view - with aligned line numbers, red-highlighted deletions, green additions, and yellow changed lines - or Unified diff view with the classic -/+ prefix format and 3 lines of context around each change. Within changed lines, character-level or word-level inline highlighting pinpoints exactly which characters differ. Options let you ignore case, collapse whitespace differences, and trim trailing spaces so you focus on meaningful changes. A live statistics panel shows lines added, deleted, changed, unchanged, and overall percentage identical. Copy the result as a standard unified diff string or download it as a .diff file. Drop .txt files directly onto either pane to load them. All processing happens 100% in your browser - your text never leaves your device.
How It Works
The tool uses the 'diff' npm library (diffLines, diffWords, diffChars) to compute an edit-distance-based diff between the two inputs. For Side-by-Side view it pairs removed/added line blocks and aligns them; for Unified view it applies a 3-line context window. Inline highlighting runs a second word- or character-level diff pass on each changed line pair.
Use Cases
- •Compare two versions of a document or article
- •Review code changes without a full IDE
- •Spot differences between configuration files
- •Verify that edits were applied correctly in any text
- •Generate a .diff patch file for sharing changes
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If you find Text Diff useful, check out these related tools: Word Counter, Case Converter, and JSON Formatter / Validator. All tools run entirely in your browser with no uploads or signups required.
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Frequently Asked Questions
What diff views are available?
What does the inline character highlighting do?
What do the options do?
Can I compare files?
Is my text sent to any server?
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