Overview
Silktide checks links inside PDFs to ensure they work correctly. Because of the way PDFs store and represent text, results can sometimes look unexpected. Most broken links reported are genuine, but PDFs do not handle links consistently. Different PDF viewers also interpret links differently, which means a link might work in one viewer but not in another.
As a result, some results may look incorrect, even though this is simply how PDFs behave.
Why this happens
PDFs do not define links in a consistent or unambiguous way. Many pieces of software that read PDFs, including Adobe, Google, Apple, Microsoft, and Silktide, can interpret the same links in different ways, or not at all.
Most PDFs are not “tagged,” so software has to guess what a link is. This ambiguity explains why a link that works in Chrome might fail in Acrobat, or why Silktide may report a broken link that looks fine to you.
How links are defined in a PDF
There are two main ways a link can appear:
1. Text links
In a PDF, you might write a web address as plain text, for example https://www.silktide.com.
PDF readers (such as Chrome or Acrobat) and Silktide all try to detect these automatically. Because this involves guesswork, results differ between platforms.
2. Tagged (annotation) links
A “tagged” PDF includes extra information that defines links unambiguously. These links are sometimes also called annotations. In theory, all PDF readers should handle these consistently.
In practice, tagging is often done incorrectly, and different readers attempt to correct bad tagging in different ways. As a result, even tagged links can behave inconsistently.
Why links in PDFs are not always what you expect
Multi-line links
Unless a PDF is tagged (which is rare), the text inside it is simply positioned shapes, not structured sentences. Complex layouts make it hard for software to decide which words belong together, so multi-line links can be misinterpreted.
Ligatures
Some character pairs, such as fi, fl, or ff, are combined into a single glyph for aesthetics.
For example:
When this happens, the underlying characters may be lost, making it impossible for Silktide or other software to reconstruct the original link.
Soft and hard hyphens
Links broken across lines may include hyphens:
www.example- website.com
This could be interpreted aswww.example-website.comorwww.examplewebsite.com.
Because PDFs rarely define this unambiguously, most software assumes the hyphen is part of the URL.
Unreadable or obfuscated PDFs
Some PDFs are deliberately created so that text cannot be machine-read. Characters may be remapped behind the scenes, so while you see meaningful text, software sees gibberish.
Text in images
If a link is written inside an image, it cannot be read unless the PDF has been properly tagged.
Doubled-up links
A link can exist both as tagged content and as text. These may not match. Silktide deliberately checks both, but PDF viewers may choose one or the other.
How Silktide shows broken links in PDFs
When Silktide flags a broken link in a PDF, the way it is highlighted tells you whether it comes from an annotation (tagged link) or from the text:
Annotation (tagged) links
These are shown with a blue border and a blue highlighter-style background inside the PDF.
In the left-hand panel, the issue will be labeled “In PDF annotation.”
Sometimes an annotation is set up incorrectly, such as only covering the first line of a multi-line link. In this case, it may look like Silktide has not highlighted the whole link, but this is a problem with how the annotation was created.
Text links
These are shown with a red border and a red highlighter-style background inside the PDF.
In the left-hand panel, the issue will be labeled “In PDF text.”
This distinction helps you immediately understand what kind of link Silktide has detected and why it may behave differently across viewers.
Identifying the cause of a broken PDF link
Once you know how Silktide highlights the link, you can investigate further:
Copy and paste the link text
If pasting produces scrambled characters, the text is not machine-readable.Click each line of a multi-line link separately
If each part behaves differently, it may be defined as multiple overlapping tags.Check in Acrobat Reader
Right-click the link, then choose Edit Link… and open the Actions tab. This shows the exact URL defined.
What should I do?
Open the PDF and check the link directly in the viewer your audience is most likely to use (for example, Chrome, Acrobat, or Edge).
If the link does not work in that viewer, the report is correct, and the link should be fixed.
If the link does work in that viewer, then:
This is likely an example of how different viewers interpret links differently. Silktide may report it as broken because the PDF does not define the link in a standard way. This can happen with both text links (red highlights) and annotation/tagged links (blue highlights).
In this case, you can safely use Ignore to dismiss the individual result, or Ignore page if an entire page is affected.
If the text looks like a link (for example
https://www.example.com) but is not clickable in any viewer, consider updating the PDF so it uses proper clickable links.
Summary
Broken link reports in PDFs are usually accurate. However, because most PDFs are not tagged and each viewer interprets text differently, some links may behave inconsistently across tools.
Silktide highlights annotation (tagged) links in blue and text-based links in red to make it clear what type of issue has been detected. This can sometimes look like a false positive, but in practice, it reflects the way PDFs work. You can safely dismiss these cases using the Ignore tools or improve the source PDF so that links are stored in a more reliable format.