pdftk

Merge PDF files

$ pdftk [file1.pdf] [file2.pdf] cat output [merged.pdf]

$ pdftk [input.pdf] cat [1-5] [10] output [pages.pdf]

$ pdftk [input.pdf] cat [1-endeast] output [rotated.pdf]

$ pdftk [input.pdf] burst output [page_%02d.pdf]

$ pdftk [encrypted.pdf] input_pw [password] output [decrypted.pdf]

$ pdftk [input.pdf] output [protected.pdf] owner_pw [pass] user_pw [pass]

$ pdftk [form.pdf] fill_form [data.fdf] output [filled.pdf]

$ pdftk [input.pdf] dump_data

pdftk input [inputpw password] [operation] [output file] [encryption options_]

pdftk (PDF Toolkit) is a command-line tool for manipulating PDF documents. It can merge, split, rotate, encrypt, decrypt, fill forms, and modify metadata without quality loss.
Page selection uses flexible syntax: ranges (1-5), specific pages (3,7,10), reverse order (end-1), and rotation suffixes (north, south, east, west). Multiple input files can be combined with per-file page selections.
Form handling fills interactive PDF forms from FDF (Forms Data Format) or XFDF data files. The dumpdatafields command extracts field information for preparing fill data. Flatten permanently merges form data into the document.
Encryption options set owner and user passwords with permission controls. Owner password grants full access; user password can have restricted permissions (no printing, no copying, etc.).
The stamp and background operations overlay PDFs, useful for watermarks, letterheads, or combining content. Attachments can embed files within PDFs.

cat

Concatenate pages (merge, extract, reorder).

Interleave pages from multiple files.

Split into single-page PDFs.

Rotate pages.

Fill form fields from FDF/XFDF.

Report PDF metadata.

Report form field information.

Update PDF metadata.

Attach files to PDF.

Extract attachments.

Apply PDF as background.

Apply PDF as foreground stamp.

Specify output file.

Input file password.

Set owner password (full permissions).

Set user password (limited permissions).

Set allowed permissions.

Use 40-bit encryption.

Use 128-bit encryption.

Flatten form fields.

Compress output.

Decompress output.

Some complex PDFs may not process correctly. Java version (pdftk-java) differs from original C++ version. Encryption is not always strong. Large files may be slow. Form filling works best with Acrobat-created forms. Some features deprecated in newer PDF standards.

pdftk was originally written by Sid Steward in 2003 using iText library. It became the standard command-line PDF tool on Linux. After the original became unmaintained, pdftk-java emerged as a port to Java, maintaining compatibility while enabling continued development.

qpdf(1), poppler-utils(1), ghostscript(1), pdfunite(1)