What is a "Diff" Tool?

A "diff" (short for difference) tool compares two versions of a file or block of text and highlights what changed between them. It's one of those utilities you don't think much about until you need it, and then you use it constantly. Added lines, removed lines, modified characters — it surfaces all of it at a glance.

Why is Comparing Text Important?

• In code reviews, before merging anything, you want to see exactly what changed — not just what the final state looks like. A good diff makes it obvious whether a change is doing what it claims to do.
• Writers and editors use diff tools too. Comparing two drafts of a document shows you where text was added, removed, or rephrased without having to read both versions side by side yourself.
• When something breaks, one of the first questions is: what changed? Comparing a config file, log output, or API response before and after a bug appeared can point you straight at the cause.
• If you work with Git, you're already looking at diffs every day. Understanding how to read a diff view is fundamental — it's how Git surfaces every commit, every PR, every merge conflict.

How Our Diff Viewer Works

It's kept simple and clean on purpose — paste your text, see the differences immediately, all in your browser.

• Paste the original text on the left and the modified version on the right. That's the whole setup.
• Instead of just flagging whole lines as changed, the tool highlights the exact characters that were added (green) or removed (red). That level of detail makes it easy to catch even tiny changes — a misplaced comma, a transposed letter, a single extra space.
• Whitespace is made visible too: unchanged spaces show as a middle dot (·) and newlines as a return symbol (↵). You'd be surprised how often a "mystery bug" turns out to be invisible whitespace.
• Everything runs locally in your browser. Your text never leaves your machine, which matters if you're diffing anything sensitive like config files or internal documents.