Preprint vs Version-of-Record Diff Tool Free & Online

See exactly what changed between preprint and published version.

What this tool does

This tool compares two versions of a text, such as a preprint and its published version of record, line by line. You paste the first version in the first box and the second version in the second box, and the tool lists the lines found only in the first version and the lines found only in the second version. Changed claims, added caveats, and removed sentences become visible without reading both versions end to end.

It works fully in your browser. Nothing is uploaded to a server, and you do not need an account. Paste your text, press the button, and read the result on the same page. That makes it useful for students, researchers, and anyone who has to get through a long paper quickly without losing the important parts.

How to use it

Paste the two versions with matching line breaks, ideally one paragraph or sentence per line, and press the compare button. Read the only-in-first list as deletions or rewordings, and the only-in-second list as additions or rewordings, then check any surprising line against the original documents, because a reworded sentence appears in both lists at once.

Worked example

A preprint with two lines, sleep improves memory and the sample was 120 students, compared with a published version that changes the second line to the sample was 118 students after exclusions, shows the first version’s sample line as only-in-first and the published line as only-in-second. The difference is small but meaningful: two students were excluded, and a careful reader now knows to ask why.

How to read the results

The output has two lists: lines only in the first text, marked as removals, and lines only in the second text, marked as additions, with counts and the line totals compared. Lines present in both versions are not shown, which keeps the diff focused on what actually changed.

Do not treat the output as a final answer. It is a starting point for your own reading. Skim the highlighted parts first, then read the full passage around anything that matters for your work. A tool can point at the likely important sentences, but only you can judge whether they are actually important for your question.

Honest limits

This is a line-level set comparison, not a word-level diff and not a semantic comparison: a reworded sentence counts as a deletion plus an addition, and a moved paragraph counts as changed even if its words are identical. It also cannot tell whether a change matters, or whether it came from peer review, editing, or correction. For a precise word-level diff of short passages, compare the changed lines by eye after this tool points at them.

This tool does not use artificial intelligence, and it does not understand your paper the way a human reader does. It follows fixed rules that you can inspect in the results. That is a strength when you want transparent, repeatable results, and a weakness when a passage needs real understanding, context, or judgement.

Tips for best results

Paste clean text. Remove page headers, footers, and reference lists before you paste, because they add noise to word counts and sentence scores. Work on one section at a time for long papers, and keep your original file open beside the tool so you can check anything surprising against the source. If you use the result in your own writing, always cite the original paper, never the tool output.

Frequently asked questions

Is it free? Yes. The tool is free to use online, with no sign-up and no download.

Is my text stored anywhere? No. Everything runs in your browser tab. Closing the tab removes your pasted text.

Can I trust the output completely? No tool of this kind should be trusted blindly. Use it to speed up reading and checking, then verify the important claims yourself in the original text.

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