Diff Checker

It compares two blocks of text and shows you exactly what changed between them. Lines that were added show in green, lines that were removed show in red, and unchanged lines stay neutral so you can see them in context. Where a line was edited rather than added or removed wholesale, it highlights the specific words that changed within that line, so a one-character tweak does not look like the whole line was rewritten. It is handy for comparing two versions of a config file, a contract, some code, or any two pieces of text.

Both, working together. The comparison is primarily line based — it works out which lines were added, removed or left unchanged. Then, when a removed line and an added line clearly correspond to one another (an edit rather than a wholesale replacement), it runs a second, word-level comparison inside that pair and highlights just the words that differ. So you get the big picture from the line view and the fine detail from the inline word highlights at the same time.

They let you ignore differences that often do not matter. With “ignore whitespace” on, lines that differ only in their leading or trailing spacing are treated as the same line, and a blank line and a line of only spaces count as equal — which is exactly what you want when one version has simply been re-indented. With “ignore case” on, “Hello” and “hello” count as identical. Turn both off for an exact, character-for-character comparison; turn them on to focus only on the changes that are meaningful to you.

They show the same comparison two ways. Split view puts the original on the left and the changed version on the right, side by side, which is the easiest way to read a before-and-after. Unified view stacks everything in a single column — removed lines then added lines, the way a Git diff or a code review looks. Split is friendlier for prose and config; unified is more compact and familiar if you spend your day in pull requests.

No. The comparison runs entirely in your browser using JavaScript — nothing you paste is sent to a server, which you can confirm in your browser’s network panel. The optional share link stores both blocks of text in the URL itself rather than on a server, and the on-device history can be cleared whenever you like. Your text stays on your machine.

Yes. It treats everything as plain text, so it works just as well on source code, JSON, CSV, logs or prose. Because it all runs in your browser, very large inputs (tens of thousands of lines) will be slower than a desktop diff tool and the rendered output is capped so the page stays responsive. For everyday comparisons — two versions of a file, a snippet before and after an edit — it is instant.