I want to compare documents
February 19, 2014 11:17 AM   Subscribe

Does publicly available software exist that lets me overlay two documents and see how they differ from each other?
posted by CollectiveMind to Computers & Internet (17 answers total) 6 users marked this as a favorite
The answer is yes! The ease of use will vary depending on the type of document. If you just want to check text fast, I sometimes use Diff Checker online.

(Also depends on your operating system and whether you are comfortable using the command line. I can think of lots of ways to compare different types of documents but they might not work for you.)
posted by mskyle at 11:18 AM on February 19, 2014 [1 favorite]

What documents are you talking about? Word documents, PDF files, images or plain text?

Various tools exist, we need to know what you want to do.
posted by Dr Dracator at 11:19 AM on February 19, 2014

If you have word documents, it is really easy to compare the two for differences. There's a built-in feature in Word to compare (and merge) different documents, and some text editors have that feature, too. Adobe Acrobat XI also does, or you can use DiffPDF (30 day trial software).

But if you're looking to compare images of documents, or even PDFs (rendered down as images), you can also load them into an image editor or related programs and change the layers in ways to display the difference in the images.
posted by filthy light thief at 11:32 AM on February 19, 2014 [1 favorite]

I use BeyondCompare in my job all the ding-danged time and I LOVE it. It's a text compare, though; for a visual compare, just scan the two images, paste one on top of the other in Photoshop and set the transparency of the top layer to 25% or so and visually inspect 'em.
posted by julthumbscrew at 11:37 AM on February 19, 2014 [1 favorite]

CompareDocs and Workshare Compare are two that I've used.
posted by Bentobox Humperdinck at 11:40 AM on February 19, 2014

It's priced for corporate use, but the best software I've used in this arena is Litera Change-Pro. It seamlessly handles Word docs, PDFs (performing OCR when necessary), plain text, and--with separately purchased plugins--even Excel spreadsheets and PowerPoint presentations. It can also save its redlines straight back into Word documents as tracked changes, something Workshare Compare couldn't do, the last time I used it.
posted by Partial Law at 11:51 AM on February 19, 2014

Like Microsoft Office, LibreOffice also offers a document comparison tool (accessed from the Edit menu).
posted by 1367 at 12:22 PM on February 19, 2014

For spreadsheets, Open Office Calc has a compare feature.

Works great with a finite number of small differences between two largely similar documents -- turns your screen into a red and black dungeon of madness otherwise.
posted by sleevener at 12:29 PM on February 19, 2014

You need to be specific about what kind of documents you want to compare.

For code I like Araxis Merge when I have a boss that will pay for it.
posted by PMdixon at 12:55 PM on February 19, 2014

Dr. Dracator, now that I think about it, I'm talking about mostly text documents. But for those documents I can't convert to text without formatting issues, then HTML and PDF docs too.
posted by CollectiveMind at 1:03 PM on February 19, 2014

All, specifically, I want to compare legislation. I want to overlay bills with laws to see how they changed. That will help identify compromises, additions and deletions.
posted by CollectiveMind at 1:04 PM on February 19, 2014

Check out Juxta Commons if you are looking to produce a scholarly comparison or commentary on the differences between witnesses. It is particularly useful when you have 2 or more witness documents.
posted by dgran at 1:04 PM on February 19, 2014

Kaleidoscope is excellent, if you are on the Mac.
posted by Silvertree at 1:12 PM on February 19, 2014 [1 favorite]

If by text you mean actual plain text, the diff program is designed to do exactly that.

I wish legislators were required to commit laws into a modern source code control system that we could more easily extract patches and see who changed what when. For instance, tumblr keeps its policies on github, which allow you to diff things like community guidelines to see what they have changed over the past year.
posted by autopilot at 3:44 PM on February 19, 2014 [2 favorites]

Using version control for laws is harder than you think. That said, there's a lot of people working in this space. Some examples:
posted by djb at 8:14 PM on February 19, 2014 [1 favorite]

Previously. Lawyers tend to use DeltaView.

I personally use diffpdf (Linux) for comparing PDFs: you can compare using different modes: appearance, characters, words.
posted by devnull at 4:24 AM on February 20, 2014

djb: Using version control for laws is harder than you think.

Yes, very much so. While some bills are only modified a bit, most undergo significant changes before they become law, so much so that would require some sophisticated software to automatically track such changes. Even then, you would still be doing constant verification to ensure the program accurately and completely captured the differences.

In my mind, it would be easier for software to highlight what parts are the same, so people could manually review changed.
posted by filthy light thief at 6:58 AM on February 20, 2014

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