Attach Files to PDF & Extract Attachments

About Attach Files to PDF & Extract Attachments

A PDF can carry other files whole. Put the source spreadsheet inside a report PDF, or the CAD file inside a drawing PDF, and one email with one file delivers both the document people read and the original they can reuse. Attached files are stored compressed inside the PDF and can be pulled out from the viewer's attachments panel.

The Attach tab adds files either as document attachments or as an icon on a specific page, and can also delete existing attachments. The Extract tab finds the attachments, sounds and media embedded in a PDF and saves them back out as ordinary files.

Document attachments versus page icons

Document attachments go into the catalog's EmbeddedFiles name tree and show up in the attachments panel. Existing entries are kept, merged with the new ones and re-sorted by name as the specification requires; a clashing name becomes “a (2).txt”. Page icons are annotations placed in a corner of one page, drawn as a paperclip, push pin, graph or tag. They suit files tied to that page's content, such as the raw data behind a chart. The icon's appearance is drawn into the file, so it shows even in viewers that don't know the icon names.

For each file the tool writes both the original name, including non-Latin characters, and an ASCII fallback, along with a description, MIME type, size, modification time and MD5 checksum. You can also set a PDF/A-3 relationship (Source, Data, Alternative, Supplement), but recording a relationship doesn't by itself make the file PDF/A-3 compliant.

Where the Extract tab looks, and staying safe

Embedded files hide in several places. The tool searches the document attachment list, associated files (AF), file attachment annotations, sound annotations and media annotations, and for a PDF Portfolio it lists the files inside the bundle too. Raw samples from sound annotations are wrapped as WAV so they play directly. If the stored MD5 doesn't match the contents, the item is flagged as a checksum mismatch, meaning the file may have been damaged or altered after it was attached.

Names containing paths like “../../” or Windows reserved names such as CON or NUL are rewritten to safe names before saving. Anything that looks like an executable, script or macro document, judged by extension and by the signature bytes at the start of the file, gets a warning. If the PDF came from someone you don't know, scan extracted files with antivirus software before opening them.

Worked examples

How to use it

1. Add the PDF; any attachments it already has are listed (use the Extract tab to pull them out).
2. Choose the files to attach and set document attachment or page icon, a description and a relationship.
3. Run, save the new PDF, and check it in the viewer's attachments panel.

Frequently asked questions

Notes

How attached files are stored as stream objects is covered in the guide “How PDF Files Work”.