How to Compare Two Texts and Find Differences Online
Paste your original text into the left input box labeled 'Original Text'. You can paste anything — plain paragraphs, code snippets, documents, or log output. The tool accepts unlimited text length, so you can compare entire documents in one session. There is no upload limit and no server involvement — all processing happens directly in your browser.
Paste the modified or updated version into the right input box labeled 'Modified Text'. Both text areas work like standard text editors, so you can paste from any application including word processors, IDEs, email clients, or websites. The tool immediately begins computing the difference as you type or paste.
Review the color-coded diff output below the input boxes. Green lines indicate text that was added in the modified version, red lines show text that was removed from the original, and uncolored lines show unchanged text. Use the statistics bar above the diff to see the total count of added, removed, and unchanged lines at a glance.
Toggle between 'Side-by-side' and 'Unified' views using the view buttons. Side-by-side view places original and modified text in adjacent columns with line numbers, making it easy to scan which specific lines changed. Unified view collapses both columns into a single column with +, −, and space prefixes, which is more compact and convenient for code reviews.
Enable the 'Ignore whitespace' option to normalize spacing differences before comparing. This is useful when comparing formatted text where tab vs space indentation or trailing whitespace differences are not meaningful to your comparison. The diff will then focus purely on substantive content changes.
Why Use UtilDaily's Free Text Diff Tool?
The Text Diff tool lets you instantly compare two versions of any text and see every difference highlighted in a clean, color-coded view — all in your browser with no data sent to any server.
- Completely free with no sign-up, no limits, and no account required — paste and compare instantly
- 100% browser-based with zero data transmission — your text never leaves your device, ensuring complete privacy
- Supports side-by-side and unified diff views with ignore-whitespace option for flexible comparison
- Works with any text format: code, documents, emails, logs, JSON, CSV, or plain paragraphs
- Instant LCS-based diff algorithm highlights every added, removed, and unchanged line with clear color coding
- No file upload required — paste text directly from your clipboard into both input boxes
- Clean, fast, and mobile-friendly interface that works on any device with a browser
Frequently Asked Questions
How does the text diff tool work?
The tool uses a line-by-line LCS (Longest Common Subsequence) algorithm to compute the minimum edit distance between your two texts. It identifies which lines were added, removed, or kept unchanged, then displays the result with color coding. Green highlights lines present only in the modified text, red highlights lines present only in the original, and unhighlighted lines appear in both versions. This gives you an exact, readable comparison of every difference between two text inputs.
Can I compare code files with this tool?
Yes. The Text Diff tool works equally well for source code, configuration files, markup, or any other text-based content. The side-by-side view with line numbers is particularly useful for code review, showing exactly which lines changed between two versions. The ignore whitespace option is helpful when comparing code where indentation style differs but the logic is the same. Since there is no file upload — only paste — the tool works in any browser without file permission prompts.
Is my text stored or sent to a server?
No. The Text Diff tool is entirely client-side JavaScript. When you paste text into the input boxes, it is processed entirely within your browser using the JavaScript engine — no data is transmitted over the network, no cookies are set, and no history is stored. You can verify this by using the tool offline after the initial page load, or by inspecting your browser's network tab while using the tool.
What is the difference between side-by-side and unified diff views?
Side-by-side view shows the original text in a left column and the modified text in a right column, with line numbers on both sides. This makes it easy to match specific lines and understand context around changes. Unified view combines both into a single column, prefixing each line with a plus sign for additions, minus sign for removals, or a space for unchanged lines. Unified view is more compact and is the standard format used in many code review tools and version control systems like Git.
Why should I use the 'Ignore whitespace' option?
The ignore whitespace option normalizes all whitespace sequences (spaces, tabs, multiple spaces) into a single space before comparing. This is useful when comparing text where formatting differences are not meaningful — for example, when a document has been re-formatted with different indentation, or when comparing output from different systems that handle whitespace differently. Enabling this option causes the diff to skip over spacing changes and focus only on substantive text changes.
How many characters or lines can I compare?
There is no hard limit on input size. The tool can handle texts with tens of thousands of lines, though very large inputs may take a moment to compute. The LCS algorithm runs in the browser and is optimized for typical document comparison sizes. For extremely large texts (hundreds of thousands of lines), you may notice slower rendering of the diff output, but the comparison itself will still complete correctly.
By UtilDaily · Updated \u2014 free, privacy-first browser tools. No sign-up, no data collection.