Compare two text blocks and see the differences highlighted. Line-by-line diff viewer.
The Text Diff Checker compares two blocks of text line by line and highlights exactly what was added, removed or left unchanged, using a color-coded diff view with a scrollable minimap for navigating large files. It uses a Longest Common Subsequence algorithm for accurate diff results, all computed locally in your browser without uploading any content. It's valuable for developers, writers and QA teams who need to audit changes between versions of text.
This text diff tool compares two text blocks line by line using a Longest Common Subsequence (LCS) algorithm - the same technique used by command-line diff utilities and version control systems like Git. Lines present in the modified text (B) but not in the original (A) are shown in green with a + prefix; lines removed from the original are shown in red with a - prefix; unchanged lines are shown in grey. The minimap on the right gives a scrollable overview of where changes are concentrated in large texts.
Yes - this text diff checker works with any plain text content, including source code (JavaScript, Python, JSON, YAML, CSS), configuration files (nginx.conf, .env, Dockerfile), SQL scripts, and documents. Simply paste the original and modified text into the two panels and the diff is generated instantly. For large files, the scrollable diff output with minimap navigation makes it easy to jump to change locations without scrolling through hundreds of identical lines.
A text diff (like this tool) operates on text content pasted into two input boxes - ideal for quick comparisons without needing to upload files or use command-line tools. A file diff tool compares files by path on a filesystem, typically using the Unix diff command or a Git diff. For most online comparison needs, pasting text is faster and more private. For version-controlled projects, git diff is more appropriate as it tracks the full history of changes across commits.
Completely. This text diff checker runs entirely in your browser using JavaScript - no text from either panel is ever sent to any server, stored, or logged. It is safe to use with confidential documents, proprietary source code, legal contracts, client data, or any sensitive content. The diff is computed locally on your device each time you type, with no network requests.
Paste the original text in the left panel (Original Text A) and the revised version in the right panel (Modified Text B). The diff result updates automatically, showing every added and removed line highlighted in colour. The stats bar at the top of the diff panel shows the total number of added and removed lines at a glance. You can copy the full annotated diff output using the Copy button to save or share the comparison result.