Text Diff / Compare
Compare two blocks of text side-by-side with color-coded additions, deletions, and modifications. Supports character-level and line-level diff for contracts, code, logs, and JSON.
Why Use Text Diff / Compare?
When a client emails you "v3-FINAL-revised.docx" after you've already implemented "v3-FINAL", hand-scanning the two is slow and error-prone. A diff tool highlights the three words they actually changed in seconds. Developers use it the same way for quick contract, config, or markdown comparisons when a full Git workflow is overkill — think comparing two .env files, two error logs, or two API response bodies that supposedly differ by one field. Because it runs client-side, you can diff legal documents or customer data without uploading them anywhere.
How to Use Text Diff / Compare
- Paste the original text in the left panel and the modified text in the right panel.
- Click 'Compare' to instantly highlight the differences between the two texts.
- Review the color-coded diff output: green for additions, red for deletions, and unchanged text in the default color.
- Switch between line-level and character-level mode if a small inline edit is hard to spot in line mode.
- Normalize line endings or whitespace first if everything appears different — common with Windows vs Unix text or pasted rich text.
Worked Examples
Spot the one-word edit in a contract clause
Left: "The Party shall deliver within 30 days."\nRight: "The Party shall deliver within 45 days."
Red: "30" • Green: "45" • Everything else unchanged.
Character-level diff catches tiny edits that line-level would miss.
Compare two error stack traces
Left: production stack trace • Right: local reproduction stack trace
All frames match except one extra middleware call on production
Line-level mode is faster for stack traces since each frame is its own line.
Audit a JSON response for a schema change
Left: yesterday's API response • Right: today's response
Added field "is_beta": true highlighted in green; everything else identical.
Pretty-print both JSON blobs first (use our JSON Formatter) so the diff aligns cleanly.
About Text Diff / Compare
The Text Diff tool lets you compare two pieces of text side-by-side to instantly spot every difference. Whether you're reviewing code changes, comparing document versions, checking translations, or auditing content edits, this tool provides a clear, color-coded visualization of all insertions, deletions, and modifications. It uses the same diff algorithm trusted by professional version control systems like Git. The tool supports character-level and line-level comparison modes, making it suitable for both prose editing and code review. All comparison happens locally in your browser for speed and privacy — your documents never leave your device.
Troubleshooting & Common Issues
The entire document shows as changed — nothing lines up
Check line endings. Text copied from Windows uses `\r\n` and from macOS/Linux uses `\n`; mixed endings cause every line to appear different. Normalize both panes to the same line ending before comparing.
Small edits inside long paragraphs are hard to spot
Switch from line-level to character-level (or word-level) diff mode. Line mode highlights the whole line as changed even if only one word differs, which buries the real edit.
Diff of JSON/XML shows every line changed after a reformat
Different formatters use different indentation (2 vs 4 spaces, tabs vs spaces). Pretty-print both sides with the same formatter before diffing, or use a structural diff tool that compares parsed JSON objects rather than raw strings.
Invisible characters make "identical" text look different
Zero-width spaces, non-breaking spaces, and BOM markers are common when pasting from rich text editors. Paste into a plain-text editor and retype problematic whitespace, or enable "show invisible characters" in your editor to hunt them down.
Frequently Asked Questions
How does the diff comparison work?
The tool uses a longest-common-subsequence algorithm (the same family Git uses) to find the minimal set of changes between two texts. Additions are highlighted in green and deletions in red for easy visual review.
Can I compare code files?
Yes. The tool works for code snippets, configuration files, and any structured text. It preserves whitespace and indentation, which is critical for code comparison.
Is there a size limit for text comparison?
The tool handles large texts efficiently, but for best performance keep each panel under 100,000 characters. Processing is done in your browser, so the practical limit also depends on your device.
Is my text uploaded anywhere?
No. The diff runs entirely in your browser using JavaScript. Sensitive content like contracts, credentials, or customer data stays on your device — nothing is sent to a server.
What's the difference between character-level and line-level diff?
Line-level marks the whole line as changed if anything in it differs — fastest for code review or stack traces. Character-level (or word-level) zooms in on the exact characters that changed — useful for prose, contracts, or one-character edits.
Why does the tool show every line as different?
Almost always a line-ending mismatch (Windows CRLF vs Unix LF) or invisible whitespace from a rich text editor. Normalize both panes to the same line ending and re-run.
Can I diff structured data like JSON or YAML?
Yes, but pretty-print both blobs with the same formatter first so the diff aligns. For deep structural diffs that ignore formatting and key order, use a parser-based tool — this one is a character/line text diff.
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