Free Text Diff — Compare Two Texts Side by Side Online
Compare two blocks of text and instantly see every difference highlighted with word-level precision. Side-by-side and inline views. Collapse unchanged lines to focus on changes. Navigate between diffs. Ignore case and whitespace. Copy unified diff output. Free, no signup, 100% client-side.
Everything You Need — Free, No Pro Plan Required
Other diff checkers lock their best features behind paid plans. We give you everything for free, right in your browser.
Word-Level Highlighting
See exactly which words changed within each modified line — not just the whole line turning red or green.
Side-by-Side & Inline Views
Toggle between split (parallel columns) and unified (single column with +/- markers) views instantly.
Line Numbers
Every line in the original and modified text is numbered so you can reference exact positions.
Focus Mode
Collapse unchanged lines to jump straight to the changes. Essential for large files with small edits.
Similarity Score
See what percentage of lines match between your two texts at a glance.
Diff Navigation
Prev/Next buttons jump between changes with a counter showing your position.
Ignore Case & Whitespace
Filter out capitalization and spacing differences to focus on real content changes.
Copy Unified Diff
Export the comparison in standard unified diff format — paste into PRs, docs, or emails.
100% Private
All processing in your browser. No uploads, no server, no tracking. Your text never leaves your device.
How to Compare Two Texts Online
1. Paste your original text in the left box. This is the “before” version — the baseline you are comparing against. The line count updates as you type.
2. Paste your modified text in the right box. This is the “after” version with your changes. The diff output updates instantly.
3. Review the highlighted differences. Green = added, red = removed. Within modified lines, changed words are highlighted with a stronger background so you can spot the exact edit.
4. Switch views. Use “Side by Side” for visual comparison or “Inline” for unified diff format. Enable “Focus changes” to collapse unchanged regions.
5. Navigate and copy. Use Prev/Next to jump between changes. Click “Copy Diff” to export in unified format. Click “Swap” to reverse the comparison direction.
When to Use a Text Diff Checker
Code review: Compare two versions of a source file to see exactly what changed before committing. Works with JavaScript, Python, TypeScript, Rust, Go, HTML, CSS, SQL, and every other language.
Document editing: Track changes between drafts of articles, contracts, emails, reports, or README files. Spot every addition and deletion without reading both versions word by word.
Configuration debugging: Compare config files (.env, nginx.conf, tsconfig.json, docker-compose.yml) between environments to find the one setting that differs between staging and production.
API response validation: Compare JSON or XML responses from different API versions or environments to verify that changes are expected and nothing unexpected slipped through.
Database migrations: Compare SQL schema dumps before and after a migration to verify that only intended columns and indexes were changed.
SEO and content updates: Compare meta titles, descriptions, H1 tags, or page copy before and after edits to verify that only intended changes shipped.
Translation QA: Compare original and translated text side by side to check that no paragraphs were skipped, duplicated, or mistranslated.
Merge conflict resolution: Paste the two conflicting versions to see all differences, decide which changes to keep, and copy the resolved output.
Frequently Asked Questions
How do I compare two texts online?
Paste the original text in the left box and the modified text in the right box. Differences appear instantly — additions in green, deletions in red, unchanged lines in the default color. No button click needed; the comparison runs as you type.
What is word-level highlighting?
Most free diff tools only highlight entire lines as added or removed. Our tool goes further — when a line has been modified (not fully replaced), it highlights the specific words that changed within that line. This makes it easy to spot a single word change inside a long paragraph.
What is the difference between side-by-side and inline view?
Side-by-side (split) view shows the original and modified text in two columns so you can compare them in parallel. Inline (unified) view shows everything in a single column with + and - markers, similar to git diff output. Use side-by-side for visual comparison and inline for copying.
What does 'Focus changes' do?
The 'Focus changes' option collapses consecutive unchanged lines into a single row showing '··· N unchanged lines ···'. This lets you skip straight to the parts that actually changed, which is especially useful when comparing large files with small edits.
Can I navigate between differences?
Yes. Use the Prev/Next buttons in the stats bar to jump between changes. The counter shows which difference you are viewing and the total count. The view scrolls to center each difference on screen.
Can I ignore case and whitespace differences?
Yes. 'Ignore case' treats uppercase and lowercase letters as equal. 'Ignore whitespace' collapses multiple spaces, tabs, and leading/trailing whitespace. Both options are useful when comparing code after reformatting or text with inconsistent capitalization.
What is the similarity percentage?
The similarity score shows what fraction of lines are identical between the two texts. 100% means the texts are identical. A low similarity (under 30%) suggests the texts are too different for meaningful line-by-line comparison.
Can I use this to compare code?
Yes. This tool works with any plain text including source code in any programming language, configuration files (JSON, YAML, TOML, .env), SQL queries, HTML, CSS, Markdown, and CSV data. Use 'Ignore whitespace' when comparing code with different indentation.
Can I copy the diff output?
Yes. Click 'Copy Diff' to copy the entire comparison in unified diff format with + for additions, - for deletions, and spaces for unchanged lines. This format is compatible with patch files, code reviews, and documentation.
Is my text sent to a server?
No. All processing runs entirely in your browser using JavaScript. Your text never leaves your device. Nothing is logged, stored, or transmitted to any server. The source code is open for verification.
How does this compare to Diffchecker?
Diffchecker is a popular diff tool, but many of its best features — word-level diff, merge, collapsible sections — require a paid Pro subscription. Our tool provides word-level highlighting, side-by-side and inline views, focus mode, similarity scoring, and diff navigation completely free with no account required.
What algorithm does this tool use?
The tool uses a Longest Common Subsequence (LCS) algorithm for line-level comparison, the same foundational approach used by git diff and the Unix diff utility. It then runs a second LCS pass at the word level within modified lines for granular highlighting.
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