Online Diff Checker — Find Every Text Difference Instantly
Paste two versions of any text and let the diff checker highlight exactly what changed. Powered by the Myers diff algorithm — the same engine that drives Git — TextCompare finds the minimal set of additions, deletions, and modifications between any two texts.
What Is a Diff Checker?
A diff checker is a tool that compares two versions of a text and identifies the differences between them. The word "diff" comes from the Unix diff command, which has been used by developers since the 1970s to compare file revisions. Today, diff checkers are essential for developers reviewing code changes, writers comparing document drafts, and anyone who needs to understand exactly what changed between two versions of any text.
TextCompare uses the Myers diff algorithm — the same algorithm that powers Git, GitHub, and most modern version control systems. It finds the shortest edit script (the minimal number of additions and deletions) needed to transform the original text into the modified text. This produces clean, accurate diffs that avoid false positives. Choose line diff for a high-level overview, word diff to pinpoint changed words within modified lines, or character diff for maximum precision down to individual characters.
All comparison runs entirely in your browser. Your text is never uploaded to any server, making this tool safe for sensitive documents, private drafts, or confidential code. The How It Works page explains the algorithm in plain language if you want to go deeper.
Tips for Reading Diff Output
Green — Added Lines
Lines highlighted in green (prefixed with +) exist in the Modified text but not in the Original. These are new insertions.
Red — Removed Lines
Lines highlighted in red (prefixed with −) exist in the Original text but were removed in the Modified version.
Amber — Modified Lines
Amber lines (~) appear in both texts but with changes. Switch to word or character diff to see exactly what changed within them.
Unchanged Context
Uncolored lines are identical in both texts and are shown as context to help you locate changes. Use unified view to scan all changes in one column.
Frequently Asked Questions
A diff checker compares two texts and highlights what changed between them. TextCompare uses the Myers diff algorithm — the same algorithm behind Git — to find the minimal set of changes (additions, deletions, modifications) that transforms the original into the modified text. Results are color-coded: green for additions, red for removals, amber for changed lines.
Line diff is the default and best for code, logs, and structured files. Word diff is ideal for document revisions where you need to spot changed phrasing within a paragraph. Character diff is the most granular — use it to catch typos, number changes, or single-character edits. You can switch modes at any time without losing your input.
Yes. Click .txt to download a plain-text patch file, or .html to download a color-coded HTML file that preserves all the highlighting. Click Share to get a compressed URL that encodes your full comparison — anyone with the link can view your exact diff without creating an account.