PDF MIME Type

About PDF document files

With application/pdf, browsers open the file in their built-in PDF viewer. Add Content-Disposition: attachment to make them download it instead. PDF content streams are usually compressed already, so gzip on the fly saves little.

• A PDF that downloads as file.pdf.html or shows as garbage was almost always sent as text/html or application/octet-stream, often by an error page or a misconfigured proxy.
• For uploads, check that the file starts with %PDF-; the type the browser reports is based only on the extension.

Other types seen for these files: application/x-pdf . Accept them when reading uploads, but send application/pdf yourself.

File signature

PDF files start with 25 50 44 46 2D ("%PDF-"). The extension and the type a browser reports for an upload both come from the file name, so check these bytes on the server before trusting a file.

Serve .pdf with the right Content-Type

Content-Type: application/pdf

application/pdf pdf;

AddType application/pdf .pdf

@pdf path *.pdf
header @pdf Content-Type "application/pdf"

curl -sI https://example.com/file.pdf | grep -i '^content-type'
# Content-Type: application/pdf

Set the type in code

res.set('Content-Type', 'application/pdf');
// Or make the browser download it:
res.attachment('file.pdf');

import mimetypes

mimetypes.add_type('application/pdf', '.pdf')  # if your system doesn't know it
mimetypes.guess_type('file.pdf')[0]  # 'application/pdf'

mime.AddExtensionType(".pdf", "application/pdf")
w.Header().Set("Content-Type", "application/pdf")

Accept .pdf uploads

<input type="file" accept=".pdf,application/pdf">

The accept attribute only filters the file picker; users can still choose another file. Listing the extension as well as the type matters, because operating systems don’t always report the type you expect.

Related types

• .docx (application/vnd.openxmlformats-officedocument.wordprocessingml.document): Word document
• .epub (application/epub+zip): EPUB e-book
• .txt (text/plain): Plain text

More documents

.doc , .xls , .xlsx , .ppt , .pptx , .odt , .rtf . Look up any extension or type with the MIME type lookup.

Sources

• IANA registration: application/pdf
• MDN: Common media types

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Frequently asked questions