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Free Text Compare Tool – Compare Text Side by Side & Find Differences

by Akshay Goswami
Free Text Compare Tool - Side by Side Diff Online | WritoryBuzz
Free Dev Tool · WritoryBuzz

Compare two texts side by side or in unified view. Highlights added, removed, and changed lines with word-level and character-level precision. Export diffs, jump between changes, and see a similarity score. The most complete free text diff tool online.

Diff Editor

Paste text to compare
View:
Original Original / Left
0 lines / 0 chars
Modified Modified / Right
0 lines / 0 chars
↔

Paste text in both panels above and click Compare to see the diff.
Supports code, prose, config files, JSON, YAML, and any plain text.

What Is a Text Compare Tool?

A text compare (or diff) tool compares two versions of a text and highlights exactly what changed between them. It shows added lines, removed lines, and unchanged lines. The WritoryBuzz Text Compare tool goes further: it highlights individual changed words within modified lines, shows a similarity score, allows exporting the diff as HTML or patch format, and lets you jump between changes with keyboard-style navigation.

Text diff tools are essential for developers reviewing code changes, writers comparing document revisions, QA engineers verifying content edits, and system administrators comparing configuration files. This tool runs entirely in your browser with no server required, meaning your content never leaves your device.

What Is the Myers Diff Algorithm?

The Myers diff algorithm, published by Eugene Myers in 1986, is the standard algorithm used by Git, GNU diff, and most modern diff tools including this one. It finds the shortest edit script between two sequences: the minimum number of insertions and deletions needed to transform one text into another.

It runs in O(ND) time where N is the sum of the lengths of the two sequences and D is the number of differences, making it fast even for large files. When you run git diff or review a pull request on GitHub, you are looking at Myers diff output. This tool uses the same algorithm to produce accurate and minimal diffs.

Side by Side vs Unified Diff View

FeatureSide by SideUnified
LayoutTwo columns: original left, modified rightSingle column with +/- prefixes
Best forSmall to medium changes, visual comparisonLarge files, patch files, Git-style output
Line alignmentCorresponding lines aligned side by sideRemoved lines before added lines
Standard formatIDE and code review tools (VS Code, GitHub)Git patch format, email patches
Whitespace useWider, requires two columnsMore compact, single column

Word-Level and Character-Level Diff

Basic diff tools mark an entire line as changed even if only one word in a 200-word sentence was edited. This tool provides two levels of sub-line highlighting:

  • Word-level diff: Within a changed line, individual words that were added or removed are highlighted. A word that was replaced shows the old version struck through in red and the new version highlighted in green. This makes it much faster to spot small edits in long lines.
  • Character-level diff: Within changed words, individual characters that differ are highlighted. Useful for spotting typos, single-character variable name changes, or punctuation differences that are invisible at the line level.

Common Use Cases for Text Diff

  • Code review: Compare a function before and after refactoring without needing a full Git setup.
  • Document revision: See exactly what changed between a first draft and a final version of a contract, specification, or article.
  • Configuration management: Compare .env files, YAML configs, or JSON settings between environments to find mismatches.
  • Content QA: Verify that an editor's changes match the brief before publishing.
  • Database query output: Compare query results between two runs to verify data consistency.
  • Translation verification: Check that a translated document has the same structure and line count as the source.
  • Log analysis: Compare two log files to find new error patterns introduced between deployments.

Privacy note: All diff processing runs entirely in your browser using JavaScript. Neither panel's content is sent to any server, logged, or stored. You can safely compare confidential code, contracts, API keys, and private documents.

What Is a Similarity Score?

The similarity score expresses how similar two texts are as a percentage from 0 to 100. A score of 100 percent means the texts are identical. A score of 0 percent means they share no common lines. It is calculated as (unchanged lines / max(left lines, right lines)) x 100. This gives a quick measure of how much a document has changed, useful when reviewing contract drafts, article revisions, or configuration updates where you want to confirm only small changes were made.

Frequently Asked Questions About Text Diff

What is a text diff tool?+
A text diff tool compares two versions of a text and highlights the differences between them. It shows which lines were added, which were removed, and which remained unchanged. The term diff comes from the Unix diff command introduced in 1974. Text diff tools are used by developers to review code changes, writers to compare document revisions, QA engineers to verify content edits, and anyone who needs to understand what changed between two versions of any plain text.
What is the Myers diff algorithm?+
The Myers diff algorithm, published by Eugene Myers in 1986, is the standard algorithm used by Git, GNU diff, and most modern diff tools. It finds the shortest edit script between two sequences: the minimum number of insertions and deletions needed to transform one text into another. It runs efficiently even for large files. When you run git diff or review a pull request on GitHub, you are looking at Myers diff output.
What is the difference between side-by-side and unified diff view?+
Side-by-side diff shows the original text in the left panel and the modified text in the right panel simultaneously, with corresponding lines aligned and color-coded. It is easier to read for small to medium changes. Unified diff shows a single column where removed lines are prefixed with minus and shown in red, and added lines are prefixed with plus and shown in green. Unified diff is the standard format used by Git patch files and code review tools.
What does word-level diff mean?+
Line-level diff marks an entire line as changed if any part of it differs. Word-level diff goes further: within a changed line, it highlights exactly which individual words were added, removed, or replaced. This makes it much easier to spot small edits like a single word change in a long sentence. Character-level diff goes even further, highlighting individual characters that changed within a word, which is useful for spotting typos, punctuation changes, or single-character code edits.
What is a similarity score in text comparison?+
A similarity score expresses how similar two texts are as a percentage from 0 to 100. A score of 100 percent means the texts are identical. A score of 0 means they share no common lines. It is calculated by dividing the number of unchanged lines by the total lines in the longer text. It gives a quick measure of how much a document has changed, useful when comparing contract drafts, article revisions, or configuration file updates.
What are common uses for a text compare tool?+
Text compare tools are used for comparing code files and pull request changes, reviewing document revisions and contract redlines, verifying content edits match a brief, comparing configuration files across environments, checking translated content matches the source structure, debugging API response differences, comparing database query outputs, and validating that deployment scripts match their reviewed versions.
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`; const blob = new Blob([html], { type: 'text/html' }); const a = document.createElement('a'); a.href = URL.createObjectURL(blob); a.download = 'diff-export.html'; a.click(); showToast('HTML exported'); } function exportPatch() { if (!diffData.length) { showToast('Run compare first'); return; } let patch = '--- original\n+++ modified\n@@ -1 +1 @@\n'; for (const r of diffData) { if (r.type === 'same') patch += ' ' + (r.left ?? '') + '\n'; else if (r.type === 'del') patch += '-' + (r.left ?? '') + '\n'; else if (r.type === 'add') patch += '+' + (r.right ?? '') + '\n'; else if (r.type === 'mod') { patch += '-' + (r.left ?? '') + '\n'; patch += '+' + (r.right ?? '') + '\n'; } } const blob = new Blob([patch], { type: 'text/plain' }); const a = document.createElement('a'); a.href = URL.createObjectURL(blob); a.download = 'diff.patch'; a.click(); showToast('Patch exported'); } function copyDiff() { if (!diffData.length) { showToast('Run compare first'); return; } let text = ''; for (const r of diffData) { if (r.type === 'same') text += ' ' + (r.left ?? '') + '\n'; else if (r.type === 'del') text += '- ' + (r.left ?? '') + '\n'; else if (r.type === 'add') text += '+ ' + (r.right ?? '') + '\n'; else if (r.type === 'mod') { text += '- ' + (r.left ?? '') + '\n'; text += '+ ' + (r.right ?? '') + '\n'; } } navigator.clipboard.writeText(text).then(() => showToast('Diff copied to clipboard')); } /* ================================================================ TOAST ================================================================ */ function showToast(msg) { const t = document.getElementById('wbToast'); t.textContent = msg; t.classList.add('show'); setTimeout(() => t.classList.remove('show'), 2200); } /* ================================================================ FAQ ================================================================ */ (function() { document.querySelectorAll('#wbFaq .wb-faq-item').forEach(function(item) { item.querySelector('.wb-faq-q').addEventListener('click', function() { const open = item.classList.contains('open'); document.querySelectorAll('#wbFaq .wb-faq-item').forEach(i => i.classList.remove('open')); if (!open) item.classList.add('open'); }); }); })();