Linearized PDF (Fast Web View): what it is and what it is for

1What is a linearized PDF?

A normal PDF stores its parts in the order they were created, and the index that explains where each page is often sits at the end of the file. To open it from the internet, the viewer would have to download almost everything before knowing what to show. A linearized PDF reorders the content and puts at the beginning the information needed to display the first page right away.

The result is that, when you open a manual of hundreds of pages from a website, you see the cover or the page you asked for almost immediately, while the rest keeps downloading in the background. It is also known as Fast Web View.

This idea was born when large files were viewed over very slow connections, and it is still useful today on mobile devices with unstable signal. Even so, many modern viewers download in parts anyway, so the practical advantage depends on the viewer, the server and the size of the document.

2How does it work under the hood?

Linearization organizes the file's objects so they are read sequentially: first the data for the first page, then a table with the location of the others, and then the rest. That way a viewer can ask the server for only the pieces it needs, if the server supports requesting parts of a file, instead of downloading everything.

It is an internal organization of the file, not a visual change. The pages, text and images are the same, and the file opens the same in any viewer, linearized or not. Viewers that don't take advantage of it simply read it like any other PDF.

3When is it worth it and when not?

It makes sense for large documents you publish on a website: catalogs, manuals, long reports or books, especially if your readers use slow connections or mobile devices. In those cases it improves the feeling of speed and reduces the wait.

It isn't needed if the file is small, if it is sent as an email attachment or if it is only used locally, because the whole file arrives anyway. Nor does it fix an excessively heavy file: before linearizing, it's better to reduce the document's size.

There is a nuance worth knowing: the benefit also depends on the server hosting the file. If the server doesn't allow requesting fragments of a file, the viewer will have to download it whole and linearization won't help. So, rather than a magic feature, it's an optimization that adds to a good publishing setup.

• Website with large PDFs: it makes sense.
• Email attachment: no benefit.
• Local file: no benefit.
• Overly heavy document: reduce the size first.

4How to check whether a PDF is linearized and how it gets lost

Many viewers show in the document properties a field called fast view or Fast Web View with a yes or a no. If it says yes, the file is linearized.

Linearization is easily lost: when editing and saving with a program that doesn't preserve it, when merging or splitting documents or when rebuilding the file. That is why it is a step done at the end of the process, right before publishing, and not at the beginning.

5Common myths

One myth is that linearizing reduces the file size; in reality the size barely changes, what changes is the internal order. Another is that without linearizing the PDF won't open from the internet; it opens perfectly, just with more waiting on large files.

It is also believed to be the same as compressing. They are different things: compressing reduces the file size, linearizing improves the order so the start shows sooner. They can be combined, but they don't replace each other.

6Linearization and Rayo PDF GO

Rayo PDF GO does not present linearization as a specific feature. It does help you prepare a lightweight document for publishing: Compress PDF reduces the size, Merge PDF and Split PDF organize the content and Delete PDF pages removes what's extra.

If you publish large PDFs on your site and need Fast Web View, check in the final file's properties whether it is enabled, and use a program that lets you save it with Fast Web View when that is your goal. Rayo PDF GO processing happens on your device.