Code Diff (Line Compare)

About this tool

Compare two versions of code or text line by line. Paste the original, a line containing only ===, then the new version.

Example

Input: old\n===\nnew

Output: - old\n+ new

Privacy

This tool runs entirely in your browser. Your data is processed locally and never uploaded to a server.

How to use this tool

1. Paste the original version of your code or text into the top area.
2. Add a line that contains only === to separate the two versions.
3. Paste the new version below that separator.
4. Run the diff to see which lines were added, removed, or changed.

Step by step, what happens

1. The tool reads your input as two blocks separated by a line with only ===.
2. It compares the blocks line by line instead of trying to understand the code structure.
3. It marks lines that exist only in the first block as removed and lines only in the second block as added.
4. When a line changed, it shows the difference so you can quickly spot what was edited.

Worked example

Here is a small text change where one line is updated and one line is added.

Input: const name = 'Ava'; console.log(name); === const name = 'Ava'; console.log('Hello, ' + name);

1. The tool splits the input at the === line into an original block and a new block.
2. It compares the two console.log lines and sees that one was changed, not just copied.
3. It keeps the unchanged name declaration as matching content and highlights the updated output line.

Tips and common mistakes

• Use a separator line with only ===. If you add extra spaces or text on that line, the tool may not split the blocks correctly.
• Keep indentation and blank lines if they matter, because the diff compares text line by line.
• If a whole block looks changed, check for small formatting edits like spaces, quotes, or line breaks.
• For the clearest result, compare one focused change at a time instead of pasting two unrelated files.

Frequently asked questions