Compare two blocks of text side by side and see every difference highlighted. Added, removed, and changed lines are color-coded so you can spot changes at a glance. Runs entirely in your browser -- nothing is uploaded.
This diff checker compares two pieces of text line by line using a longest common subsequence (LCS) algorithm. It identifies which lines are identical, which were added, which were removed, and which were modified. The result is a clear, color-coded view of every change between the original and modified text.
Developers use diff checkers to review code changes before committing, compare configuration files across environments, or verify that automated edits applied correctly. Writers and editors rely on them to track revisions between drafts. System administrators compare log files or server outputs to spot unexpected changes. Any time you need to understand exactly what changed between two versions of a text, a diff checker gives you the answer in seconds.
A diff checker is a tool that compares two blocks of text and highlights the differences between them. It shows which lines were added, removed, or changed, using color-coded markers so you can quickly see every modification. Diff checkers are essential for code reviews, document editing, and any task where you need to track changes between two versions of a file.
The side-by-side view places the original text on the left and the modified text on the right, with matching lines aligned horizontally. This makes it easy to compare corresponding sections visually. The unified view combines both texts into a single column, prefixing removed lines with a minus sign and added lines with a plus sign. Unified view is more compact and is the standard format used by version control systems like Git.
Yes. This diff checker runs entirely inside your browser using JavaScript. Your text is never sent to a server, stored, or logged anywhere. You can verify this by opening your browser developer tools and monitoring the Network tab while comparing text. This makes it safe for comparing sensitive documents, source code with credentials, and confidential content.
This tool uses a longest common subsequence (LCS) algorithm, the same foundational approach used by Unix diff and Git. It finds the longest sequence of lines that appear in both texts in the same order, then classifies every other line as either added or removed. Lines that exist at the same position but with different content are marked as changed. This produces accurate, minimal diffs for texts of any size.
Absolutely. This diff checker works with any plain text, including source code in any programming language, configuration files such as JSON or YAML, SQL queries, shell scripts, and markup languages like HTML or Markdown. The monospace font and line numbers make it well-suited for code comparison. Simply paste your original code on the left and the updated version on the right, then click Compare.