Text Diff Checker

Text Diff Checker is a free online tool that compares two blocks of text and highlights the differences between them. It clearly shows additions, deletions, and modifications, making it easy to see exactly what changed between two versions of a document, code file, or any text content.

The tool supports both word-level and character-level comparison modes, allowing you to choose the granularity that best suits your needs. Whether you are reviewing code changes, tracking document revisions, or proofreading edited content, the visual diff makes it simple to spot every modification.

All comparison processing happens locally in your browser, so your text data remains completely private. The tool works with any type of text including code, prose, configuration files, and more, up to a few thousand words per side, because the comparison is rebuilt in full every time either text changes.

Choosing the comparison level changes what you see. Word level is the right default for prose, since it shows a changed sentence as a few altered words rather than as a wall of character-by-character noise. Character level is better for code, identifiers and anything where a single letter matters. The differences that catch people out are the invisible ones. Two files that look identical often differ in line endings, because Windows ends lines with a carriage return and a line feed while everything else uses a line feed alone, and that difference is real to a diff and invisible on screen. Trailing whitespace behaves the same way. A non-breaking space pasted from a web page or a word processor is another: it looks exactly like a space and is a different character.

Try this diff text checker on one short line to see how the result is counted. Type The quick brown fox as the Original text and The quick red fox as the Compared text, with Compare by set to Word. The Comparison result shows brown struck through in red, red highlighted in green, and the rest plain, and the counters read Common: 6, New: 1, Removed: 1. Common is 6 rather than 3 because the spaces between words are counted as tokens too. Switch to Character and the same edit is broken into single letters, which is the view this text compare tool offers for identifiers and codes.