PDF Attachments Viewer

PDF file attachments — formally called embedded file streams — are defined in section 7.11.4 of the PDF specification (ISO 32000-2:2020). They reside in the document catalog's /Names dictionary under the /EmbeddedFiles name tree. Each entry in this tree maps a string key to a file specification dictionary (/Filespec), which in turn points to the actual file data stored as a compressed stream object.

A file specification dictionary contains several keys that describe the attached file. The /UF key holds the Unicode filename, while /F provides a backward-compatible ASCII filename. The /EF (embedded file) dictionary links to the stream object that holds the raw bytes. Additional metadata can include a /Desc description string, MIME type via /Subtype, creation and modification dates, and a checksum for integrity verification.

The name tree structure uses a balanced tree of intermediate nodes (containing /Kids arrays) and leaf nodes (containing /Names arrays of alternating key-value pairs). This design allows efficient lookup in PDFs with hundreds of attachments. This tool walks the entire tree recursively, collecting every leaf entry regardless of tree depth, so it can discover attachments that simpler parsers might miss in deeply nested structures.

Attachments differ from annotations in an important way. Annotations are per-page objects stored in each page's /Annots array — they are visual overlays like highlights and comments. Attachments are document-level objects independent of any page. They do not render visually within the PDF content; instead, viewers that support them display an attachment panel or paperclip icon. Tools like PDF Remove Annotations handle per-page annotation objects, while this tool focuses exclusively on the document-level EmbeddedFiles tree.

When removing attachments, the tool deletes the corresponding file specification dictionaries and stream objects from the name tree. If all attachments are removed, it also deletes the /EmbeddedFiles key entirely, and if the /Names dictionary becomes empty, it is removed from the catalog too. For partial removal, the tool rebuilds a flat name tree containing only the retained entries. This approach produces a valid, compact PDF structure without orphaned references.

Managing PDF attachments is essential in several common document workflows:

• Extracting supporting data — Government filings, scientific papers, and financial reports often embed source data as spreadsheets, XML files, or supplementary PDFs. Readers need to extract these files to analyze the underlying data. XBRL filings submitted to the SEC, for example, embed taxonomy schemas and instance documents as PDF attachments.
• Reducing file size before sharing — Attachments can add megabytes to a PDF without being visible during normal viewing. A contract PDF with embedded original Word documents, revision histories, or font files quickly balloons in size. Stripping attachments before email distribution or archival storage reclaims that space. Use PDF Compress afterward for additional size reduction.
• Security and compliance review — Embedded files can carry malware, macros, or executables concealed inside an otherwise innocent-looking PDF. Security teams inspect attachments before allowing PDFs into controlled environments. Regulatory compliance may also require stripping attachments from documents before public release to prevent accidental disclosure of internal files.
• Discovering hidden content — Many PDF viewers — including Chrome's built-in viewer, Safari Preview, and most mobile apps — do not display attachment panels. Users receiving such PDFs may not realize files are embedded. This tool surfaces every attachment regardless of which viewer created or last opened the document. Related tools like PDF Edit Metadata and PDF Sanitize help examine other hidden document properties.
• PDF/A archival preparation — The PDF/A-3 standard (ISO 19005-3:2012) is the only PDF/A variant that permits embedded files, and even then only with specific MIME type declarations. Converting a PDF to PDF/A-1 or PDF/A-2 requires removing all attachments first. Stripping embedded files is a prerequisite step in many digital preservation workflows.
• Document forensics — Legal discovery and e-discovery processes often require cataloging every file embedded in a document set. Listing attachments with their names and sizes creates an inventory that investigators can cross-reference against known file hashes or naming patterns. Inspecting PDF Page Dimensions and PDF Flatten are complementary steps in forensic document review.

All processing happens locally in your browser using client-side JavaScript. Your PDF and its embedded files never leave your device — no upload, no cloud storage, no third-party access. This makes the tool appropriate for sensitive documents including legal filings, medical records, financial statements, and proprietary data packages that cannot be transmitted to external servers.