Text Compare Tool
New PopularFree online text compare tool with real-time diff — no button click required. Uses the Myers diff algorithm (same as Git) to find the minimum edit distance between two texts. Highlights added lines (green), removed (red), and modified (yellow) with character-level precision inside each changed line. Features: side-by-side and inline view, merge editor with accept/reject per change, moved block detection, syntax highlighting for 20+ languages, diff statistics dashboard, readability comparison, word frequency analysis, shareable comparison URLs, and Web Worker support for files with 10,000+ lines.
Compare two texts to use the Merge Editor.
The Merge Editor lets you accept or reject each difference individually,
then download the final merged result.
How to Use
Paste the original text on the left and the modified version on the right. Or drag-and-drop any text file directly into either panel. The comparison starts instantly — there is no Compare button.
Every change is highlighted: green for additions, red for removals, yellow for modifications, with character-level precision inside changed lines. Use the ◀ ▶ navigation buttons to jump between each change.
Switch between side-by-side or inline view, choose line, word, or character diff level, toggle dark/light theme, select a language for syntax highlighting, and use options like ignore case, ignore whitespace, or collapse unchanged sections.
Use the Merge Editor to accept or reject individual changes and download the final merged text. Export as HTML, PDF, or standard unified diff patch. Share the comparison via a URL — data is encoded in the URL, nothing stored on any server.
What Is a Text Compare Tool?
A text compare tool (also called a diff checker or text diff tool) finds and highlights every difference between two versions of a text. This is essential for developers reviewing code changes, writers comparing document drafts, editors tracking revisions, translators comparing source and target text, and SEO professionals auditing content between versions. Every time you wonder "what exactly changed between these two versions?" — a diff tool gives you the answer.
Why This Tool Is Different
Most diff tools require you to type both texts and then click a "Compare" button. Our tool compares in real-time as you type or paste — results appear instantly. Most tools also only show line-level differences. Ours goes further: within each changed line, we highlight the exact characters that changed, so you can spot a single-letter typo or a changed variable name at a glance.
- Real-time diff — No Compare button. Results update as you type (debounced 300ms).
- Character-level precision — Within modified lines, highlights the exact characters that changed, not just the whole line.
- Move detection — If a paragraph is relocated rather than rewritten, we detect it as a "move" (shown in blue) rather than a deletion + addition.
- Merge Editor — Accept or reject each difference individually. Diffchecker charges for this feature — we include it free.
- Diff Statistics Dashboard — Similarity percentage, added/removed/changed/moved counts, and full line/word/character breakdowns.
- Readability Comparison — See how Flesch Reading Ease, grade level, and reading time changed between versions.
- Word Frequency Analysis — Discover which words were introduced, removed, or changed in frequency between drafts.
- Syntax Highlighting — 17+ programming languages auto-detected, making code comparison much easier to read.
- Shareable URLs — Share a comparison via URL. Data is compressed and stored only in the URL hash — never on our servers.
How It Works: The Myers Diff Algorithm
Under the hood, the comparison uses the Myers diff algorithm — the same algorithm Git uses to compute git diff. It finds the minimum edit distance between two texts: the shortest sequence of insertions and deletions that transforms the original into the modified version. This produces the most readable diff with the fewest spurious changes. For large files (10,000+ lines), the comparison runs in a Web Worker to keep the UI responsive.
Privacy
All comparison, syntax highlighting, merge editing, and export happens entirely in your browser using JavaScript. Your text is never transmitted to any server, never stored, and never shared. When you use the Share feature, both texts are compressed and encoded directly in the URL — no database, no backend, no tracking.
Frequently Asked Questions
We use the Myers diff algorithm — the same algorithm Git uses for git diff. It finds the minimum number of insertions and deletions needed to transform the original text into the modified text, producing the most readable diff with the fewest spurious changes. Within each modified line, we run a secondary character-level comparison to highlight exactly which characters changed.
No. Unlike other diff tools, our comparison updates in real-time as you type or paste. There is no Compare button — results appear within 300 milliseconds. For very large files (10,000+ lines), a brief processing indicator appears while the comparison runs in the background, but the page never freezes.
Yes. We support syntax highlighting for 17+ programming languages and formats including JavaScript, TypeScript, Python, Java, C#, PHP, HTML, CSS, JSON, XML, SQL, Markdown, Go, Ruby, and YAML. The language is auto-detected from the content, or you can select it manually from the dropdown. The highlighting is applied to both panels simultaneously.
The Merge Editor lets you go through each detected difference and decide whether to accept it (use the modified version) or reject it (keep the original). You can accept and reject changes individually or use bulk actions. A live preview shows the merged result updating as you make decisions, and you can copy or download the final merged text when you're done.
When a paragraph or code block is moved from one location to another (relocated without being rewritten), most diff tools show it as a deletion in the old position and an insertion in the new position. With Move Detection enabled, we identify these relocations and show them in blue/purple instead of red/green, making it clear that the content moved rather than changed.
It treats differences in indentation, extra spaces, and consecutive whitespace as non-changes. This is essential for code comparison where formatting may differ between versions (e.g., different indentation styles or linting rules applied) but the actual logic is identical. Combined with "Ignore Line Endings", it's also useful for cross-platform comparisons between Windows (CRLF) and Unix (LF) files.
No server storage, ever. When you click Share, both texts are encoded directly into the URL using base64 encoding. Anyone with the URL sees the same comparison — your data travels with the link, not through our servers. For very long texts, the URL may exceed 8,000 characters which some platforms (like Twitter) may truncate. In that case, we'll warn you before copying.
There is no hard limit. For texts under 10,000 lines, comparison is instantaneous. For larger files, the diff runs in a background Web Worker so the page stays responsive, and a progress bar shows completion percentage. Files with 50,000+ lines may take a few seconds but will complete. The practical limit depends on your browser's available memory.