What adding an attachment means
New files are stored as document-level attachments in the PDF EmbeddedFiles name tree.
Adding a file does not convert its contents into visible PDF pages.
Word, Excel, ZIP, XML, images, text and other PDF files are treated as bytes, not executed content.
Attachments increase the PDF size by approximately their stored data plus PDF overhead.
Duplicate names can be replaced, renamed automatically or skipped.
Writing attachments normally invalidates an existing digital signature.
Embed multiple file types
PDF attachments can store arbitrary file data. Setpdf accepts common office files, archives, images, XML, text and PDFs without opening, rendering or converting them. The receiving reader and operating system determine how those files can be opened.
Names, descriptions and duplicates
Each added file receives a safe base filename and an optional description. When a name already exists, choose to replace the existing attachment, create a numbered name, or skip the new file. Paths and control characters are removed.
Size and reader visibility
Embedded bytes make the output PDF larger. Some desktop readers show an attachment panel, while browser or system viewers may not expose it clearly. The attachment can still be present even when a reader hides it.
Capability boundaries
Setpdf adds document-level attachments; it does not place a file-attachment icon at a page coordinate. It does not unpack ZIP files, preview content, run executables, certify files as safe or turn attachment content into pages.
File and password handling
The source PDF and added files are uploaded to a temporary Setpdf worker using random filenames. Content, original names, descriptions and PDF passwords are not logged. Every input, output and temporary file is deleted after success, failure or timeout. Count, size, page, time and memory limits protect the service.
Adding attachment questions
Can I add Word, Excel, ZIP or XML files?
Yes. These and other file types can be embedded as document attachments, subject to size and count limits.
Will the attachment appear as a PDF page?
No. Embedding stores a separate file inside the PDF. Convert or merge content separately if it must become visible pages.
What happens when an attachment name already exists?
For each added file you can replace the existing attachment, create a unique numbered name, or skip that file.
Does adding files change page content?
The worker preserves pages, order, dimensions, bookmarks and ordinary metadata while adding the attachment name tree entries.
Will a digital signature remain valid?
Normally not. Adding attachments rewrites PDF bytes after signing and usually invalidates signature verification.
Does Setpdf open or scan my added files?
Setpdf does not execute, render, preview or unpack them and does not claim they are safe. Recipients should scan unfamiliar files before opening.