This is an experimental feature.
With PDF++, you can seamlessly integrate PDF files located outside your vault as if they were inside.
For example, PDF++ allows Obsidian's built-in PDF viewer to open PDF files from the Internet or located externally on your local file system.
Backlink highlighting works consistently across all PDFs, regardless of their location within or outside the vault.
Thanks to this feature, you can manage PDF files without saving their actual contents in your vault folder. As a result, you don't need to worry about the storage limit of Obsidian Sync anymore, for example.
For local PDF files, use symbolic links instead if possible.
See also the following page from the official help docs: https://help.obsidian.md/Files+and+folders/Symbolic+links+and+junctions
PDF++ uses "dummy" PDF files to achieve these functionalities. A dummy PDF file acts as a proxy for an actual PDF file that lives outside your vault.
A dummy PDF file is a plain text file that
.pdf,https://, http:// (for PDFs on the web) or with file:/// (for local PDFs), andFor file:///, notice there are three slash signs.
Don't worry, there are also easier ways - but let's create a dummy PDF file manually just to get the idea.
For example, open your favorite text editor and create a text file with the following content:
https://pdfobject.com/pdf/sample.pdf
Then, save it as example.pdf.
Again, a dummy PDF file is just a plain text file although the extension .pdf looks as if it were an actual PDF file.
Open example.pdf in Obsidian. Then, the following PDF file will be displayed in the built-in PDF viewer: https://pdfobject.com/pdf/sample.pdf.
It looks as if a normal PDF file located in your vault, and various PDF-related features work the same - you can copy a link to a text selection, embed a rectangular selection, highlight backlinks, and so on.
PDF++ offers several ways to make the creation of dummy files easier: with drag & drop, via a command, and by a bookmarklet.
While holding Shift (by default), drag and drop a PDF file from your OS's file manager (Finder, File Explorer, etc.), or from your browser, to Obsidian's editor to create a dummy file and insert a link to it.
You can customize which modifier key to use (or not to use any key) in the settings. By choosing "None" or Option (macOS) / Ctrl (other), you can override Obsidian's built-in drag-and-drop actions if you want to.
Note that this does not work on mobile.
Dragging from your browser will work whether you are on a desktop or mobile device like an iPad. Note that on mobile, you might need to start holding Shift (or any modifier key you choose in the setting) before dragging.
You can also create dummy files using the PDF++: Create dummy file for external PDF command.
You can create a bookmarklet for quickly creating dummy files from your browser.
See here for the details: Bookmarklet to create dummy PDF files.
You can specified the default save location of dummy PDF files in the settings. By default, they are saved in the same folder as Obsidian's attachment folder (Obsidian Settings > Files and links > Default location for new attachments).
You can also choose a different folder. For example, using a dedicated folder for dummy PDF files might be helpful for later file management.
There is one thing you cannot do for external PDF files: editing/modification; external PDFs are read-only in some sense.
Moreover, the loading speed might also be an issue if the PDF is fetched from the Internet.
To resolve these problems, you can "import" an external PDF file into your vault.
It means that the actual binary content of the external PDF is saved in the dummy PDF.
The dummy PDF is no longer a dummy, but instead, it's now an actual PDF file.
There are two ways to import an external PDF file:
Run the Open this PDF in the original location command while opening an external PDF file to open it in the original location.
If it's in the local file system, the OS-defined default PDF viewer will be opened. If it's on the web, the browser will open the original file.
Note that dummy PDF files do not follow the PDF specification and thus cannot be recognized by other PDF viewer applications such as Adobe Acrobat.
If PDF++ stops working, they will not displayed properly even in Obsidian.
However, they are just plain text files so you can easily open them with any text editor, and then replace them with actual PDF files.
It is pretty easy to distinguish dummy & actual PDFs because the actual ones always start with a string of the form "%PDF-x.y". It is trivial to write a tiny script (in Python or whatever language) that checks if a given PDF file is a dummy or not. Even if you don't know how to code, you can just open the file as a plain text file using any text editor to check its content. In practice, you will also be able to use file sizes because dummy PDFs are <= 300 bytes, which is a unusually small size for PDFs.
The icon was taken from Lucide.
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Copyright (c) for portions of Lucide are held by Cole Bemis 2013-2022 as part of Feather (MIT). All other copyright (c) for Lucide are held by Lucide Contributors 2022.
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