Text Diff Checker

Does this diff checker upload my text or documents to any server?

No. All diff processing happens entirely inside your browser using JavaScript. Your text, pasted content, and dropped files never leave your device, making the tool completely private and secure.

What is the difference between side-by-side and inline diff modes?

Side-by-side mode shows the original text on the left and the modified text on the right, with synchronized scrolling. Inline mode combines both changes into a single stream, marking insertions in green, deletions in red, and replacements inline. Choose the format that suits your workflow.

How does JSON mode work?

When JSON mode is enabled, the tool automatically pretty-prints JSON on both sides before comparing them. This makes structural differences (added fields, modified values, reordered blocks) easy to spot. Invalid JSON input is ignored, and the tool falls back to raw text.

What does 'Ignore whitespace' and 'Ignore case' do?

Ignore whitespace removes extra spaces and trims line endings before comparison. Ignore case converts both texts to lowercase for matching. These options are useful when formatting changes should not count as actual modifications.

Why do replacements show word-level highlights?

When a line is changed on both sides, the tool performs a detailed word-level diff. Inserted words are highlighted in green, deleted words in red, and unchanged words are left normal. This makes it easier to see exactly what changed within each line.

Can I drop files into the text boxes?

Yes. You can drag and drop plain text files such as .txt, .json, .log, or .md directly into the left or right text areas. The file content is loaded instantly, and no data is uploaded anywhere.

Why does the tool switch to a simpler diff for very large inputs?

For extremely large text sizes, the algorithm automatically switches to a fast fallback mode to prevent your browser from freezing. This mode still shows correct line-level changes, but may skip detailed word-level analysis for performance reasons.

How do keyboard shortcuts work?

You can press Ctrl+Enter (or Cmd+Enter on Mac) to run the diff quickly. Pressing Ctrl+W toggles word-wrap on and off. These shortcuts help speed up editing and reviewing differences.

Why are the scroll positions synchronized?

In side-by-side mode, horizontal scrolling is kept in sync so that differences across both panes line up visually. This prevents confusion when viewing long lines or wide code blocks.