About PaperDiff

PaperDiff compares two documents and tells you what changed. It is built and run by Damien Yvert, an independent developer, and it is one of a small number of single-purpose web tools I maintain: a resume builder, a chart maker, a video compressor, a photo culler. They have one idea in common, and it is the reason this one exists.

The idea: the file should not have to go anywhere

Browsers can do far more than they are usually asked to. A tab can parse a PDF, unzip a Word document, decode video, run a diff over a hundred thousand words. For most of the tasks people reach for a web tool to do, the server in the middle is not doing anything the browser could not. It is there because it is how software is usually built, and because it makes the thing easy to bill for.

The cost of that server is paid by whoever uploads the file. Sometimes that cost is nothing. Sometimes the file is a draft agreement under negotiation, a medical report, a tender response or an employment file, and uploading it is a disclosure to a third party that the person doing it may not be entitled to make. The whole of this tool exists in the gap between those two cases.

So there is no upload endpoint on this site. Not an upload with a short retention policy, none at all. You can confirm it in under a minute: open your browser’s network inspector, compare two documents, and watch nothing leave the page. Or load the page, disconnect from the network, and compare them anyway.

Why this one was worth building

Document comparison is a solved problem with an unsolved distribution. The established tools are good and are priced per seat per month, which is right for a team doing it all day and absurd for someone checking two drafts this afternoon. The free online ones are free because they upload both files to a server, and if you read the threads where people ask for a recommendation, that is the complaint that comes up every time.

What was missing was the third thing: free because it costs nothing to run, and private because there is nowhere for the documents to go. That turns out to be the same property viewed twice.

What it is not good at

It cannot compare scanned documents, because a scan contains pictures of words and there is no text in it to compare. It cannot write a Word file with real revision marks in it. It does not integrate with Word, Outlook or a document-management system, and there is no shared workspace or audit trail. Those all need a server, and a server would need paying for, and paying for it would bring back the metering and the upload.

If any of them is what you need, buy the paid tool: it is the right answer and I say so on the comparison page. If what you need is “tell me what changed, and do not send my contract anywhere”, that is this.

How it is paid for

It is not, currently. There is no advertising, no account, no affiliate link and nothing to buy. If a paid tier ever appears it will be a one-time payment for additions (batch comparison, export with revision marks) and never a cap on what is free today. One of my other tools works exactly that way, and the commitment is the same here: the free version is the whole tool, not a sample of it.

The example documents offered on the home page are invented boilerplate written for that purpose. They are not a contract, not a template, and nothing in them is drafting anybody should use.

Getting in touch

Bug reports, documents it reads badly, and formats it should read are all welcome: a PDF it mangles is the most useful thing anyone can send me, and it does not need to be the real document. The address is on the legal notice, along with who publishes the site.