How links work in PDF by Zaweba

Links turn a PDF from a printed page on a screen into something you can move round. A contents page that jumps to its chapters, a reference that opens the website it cites, a set of documents that point to one another: all of these depend on links working properly. In PDF by Zaweba they do, with a sensible check before anything leaves the app.

What counts as a link

Two kinds of thing are clickable. The first is a link annotation, the kind made deliberately when the PDF was created, usually over a contents entry, a cross reference or a button. The second is a web address simply written in the text. Plenty of PDFs print a website or email address without ever making it a proper link, and the app makes those clickable too, so you aren't left copying and pasting them.

When the pointer passes over a link it turns into a hand, and a tooltip shows where the link goes. That tooltip is worth reading before you click, especially in a document from someone you don't know.

Where links take you

A page link jumps within the document. Click an entry on the contents page and you are on the chapter. Previous view, on Alt+Left, brings you back to where you were, which makes it easy to follow a cross reference and return.

Web and email links open in your browser or mail program, but only after asking. There is a setting for this with three choices: ask, always or never. Alongside it is a list of trusted sites. Add the addresses you use all the time, your company's own site perhaps, and those open without a question while everything else still asks.

A link to another PDF opens that PDF, in the app, so a set of linked documents behaves like one collection.

Relative links and the base web address

Some PDFs contain links that only say part of an address, such as a page name without the website in front. On the site they came from those work, but in a downloaded copy they lead nowhere. File > Base web address for links sets the base that these relative links open against. Fill in the site the document belongs to and its partial links start working again.

This mostly matters for documentation and reports exported from websites, where every internal link was written relative to the site.

Staying safe with links

The ask setting is the right default. Links in a PDF can lead anywhere, and the address shown on the page isn't always the address underneath. Asking first gives you the chance to look at the real address. It also stops a click that was meant to select some text from suddenly opening a browser window.

Choose always only if you work with your own documents and find the question gets in the way. Never suits a locked down PC where web pages shouldn't be opened from documents at all. Trusted sites are the comfortable middle: fewer questions for the places you know, the safety check for everything else.

How it fits the rest of the app

Links work hand in hand with bookmarks, named destinations and the go to page command. Bookmarks give the outline, links give the shortcuts inside the text, and previous and next view tie the jumps together. With all of them working, a long linked report in PDF by Zaweba reads more like a small website than a stack of pages.