Diff Checker

What is a Diff Checker?

A diff checker compares two pieces of text and shows you exactly what changed between them — which lines were added, which were removed, and which stayed the same. It is an essential tool for reviewing code changes, comparing document revisions, auditing configuration file updates, and debugging unexpected differences between two data exports.

How to compare two texts online

1. Paste the original text in the left pane and the modified text in the right pane. You can also drop files directly.
2. Choose Line diff for comparing documents, Word diff for spotting specific wording changes, or Char diff for character-level precision.
3. Toggle Side-by-side (original left, modified right) or Inline (unified view with +/− prefixes).
4. Enable Ignore whitespace to skip formatting changes, or Ignore case to treat capitalisation as irrelevant.

Side-by-side vs inline — when to use each

Side-by-side view displays the original and modified texts in two columns with corresponding lines aligned. It is best for reviewing long documents where you want to see the before and after in context simultaneously.

Inline view shows a single column with added lines in green and removed lines in red — similar to git diff output. It is more compact and works better on small screens or when the changes are concentrated in a small area.

Privacy when comparing text files

Configuration files, environment files, database exports, and code you paste into a diff tool can contain secrets, passwords, API keys, and proprietary logic. Many online diff tools process text on the server — exposing your data to logging and retention. This diff checker runs the diff library entirely in your browser. Nothing is transmitted. The shareable URL encodes both texts in the URL hash using LZ-string compression, so sharing works without any server involvement.