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Word-Level Diff — Compare Text by Word

Two drafts, one list of the words that actually changed. Line breaks are ignored, and the reading happens on your machine.

Original
Changed

How word-level comparison works

Prose has no respect for line numbers. Rewrap a paragraph from eighty columns to a single long line and a line-oriented comparison will declare the entire passage rewritten, though not one syllable moved. This mode avoids that by throwing line structure away before it starts: both documents become one continuous stream of whitespace-separated tokens, and the shortest edit script is computed across that stream. Alter "thirty days" to "sixty days" inside a four-hundred-word clause and what comes back is two marks — one removal, one insertion — while the remaining tokens stay quiet, no matter where either version happens to break its lines.

Runs of whitespace are normalised as part of tokenizing, so a double space collapsing to one, or a newline becoming a plain gap after an export, never registers as an edit. If that is precisely the layer you need to inspect, Character Diff preserves every space, tab and line ending instead. Matching stays case-sensitive unless you switch it off, which is useful when the only question is whether a defined Term lost its capital letter. Recomputation happens roughly two-tenths of a second after you stop typing, in a Web Worker, so a manuscript of several hundred pages does not freeze the cursor. For prose kept in Markdown, where you want the rendered result checked as well as the source, Markdown Diff handles both layers at once.

Unsigned drafts stay on your machine

Documents that get compared word by word are usually the ones nobody has signed yet: a redlined master services agreement, a settlement draft, a manuscript still under an option, an announcement sitting behind an embargo. Putting any of those through a web form creates a copy you no longer govern. That cannot happen here, because the comparison is JavaScript executing in your own browser — no account, no draft saved anywhere, nothing written to a server at any point. Open your browser's network tab while you use this tool — you'll see no request carries your content. The verification steps are written out here.

Who compares prose this way

  • A paralegal collating a fourth-round redline places the version opposing counsel returned beside the one the firm sent, and reads the actual changed wording rather than trusting that every edit came back tracked.
  • An editor handing back a copyedit shows an author exactly which phrases were cut, while the line breaks that a word processor reshuffled during export stay invisible in the result.
  • A communications lead ten minutes from an embargo checks the release about to hit the wire against the copy legal approved that morning, looking only for the qualifier someone might have dropped.
  • A translator quoting for a revision identifies which sentences the client altered in a twelve-thousand-word English source, so only those paragraphs go back through translation instead of the whole file, and the quote reflects real work rather than a guess.
  • A doctoral candidate answering a supervisor reconciles the chapter emailed back with the copy on the laptop, because two rounds of comments arrived out of order and nobody is certain which revisions survived the merge.

Frequently asked questions

When is word mode better than line mode?

Any time line breaks are an artefact rather than meaning: contracts, articles, chapters, email drafts, anything that has been reflowed by an editor or a mail client. Keep line mode for material where a line is a real unit — configuration files, logs, code, tabular exports — because there the position of a break is information worth seeing.

How long a document will it take?

A full-length novel of about 120,000 words lands near 700 KB, which stays inside the live-comparison budget of 1 MB combined. Above that you get a Compare button instead of automatic recomparison, and roughly 10 MB per side remains comfortable. The absolute ceiling is 50 MB, well past anything you would read as prose.

Is my draft uploaded when I paste it?

It is not. There is no upload step in this page at all — the token comparison happens in a worker thread on your own device, and closing the tab is the entire deletion process. Our privacy page explains how to confirm that in DevTools in under a minute.

Can it read tracked changes from a Word file?

Not yet. Paste or drop plain text and the revision marks in the original document are ignored, which is often the point — you see what genuinely differs rather than what someone remembered to track. Native .docx comparison, including accepted and rejected revisions, is on the roadmap.

How do I send the marked-up version to a colleague?

Share encodes both drafts into the part of the link after the # symbol, which browsers never transmit to any server, so the recipient reconstructs the comparison locally. Compressed links are capped at 8 KB; longer documents get a self-contained HTML report you can email as an attachment instead.