qpdf — The Complete Guide: Repair, Decrypt and Merge PDFs Without Touching the Content
qpdf is a command-line tool and library that makes structural changes to PDF files without touching what you see on screen. When another program fails to open a file, when you need to remove a password from a document you were given the password for, or when hundreds of reports must be merged in a script — qpdf is the right helper. It is open source under the Apache 2.0 licence and free for any use.
qpdf
qpdf project (Jay Berkenbilt)
Command-line tool to repair, encrypt and decrypt, merge and split PDFs and inspect file structure — without changing the content.
Get it from the vendorWhat you get
- File repair — rebuilding the structure of damaged files.
- Encryption and decryption — adding or removing passwords and restrictions.
- Merge and split — picking pages from several files into one.
- Fast web view — preparing a file for progressive loading in the browser.
- Structure inspection — showing the objects in a file and checking it.
Usage examples
Check a file: qpdf --check report.pdf. Merge: qpdf --empty --pages a.pdf b.pdf -- merged.pdf. Remove the password from a file you are allowed to open: qpdf --decrypt --password=SECRET in.pdf out.pdf. There is no GUI, and the tool does not convert formats, compress images or run OCR.
Related tools
For stamps and form filling on the command line — PDFtk. For compression and rendering to images — Ghostscript. For adding a text layer to scans — OCRmyPDF.
PDFtk
PDF Labs
Classic PDF toolkit: merge, split, rotate, stamp and fill forms from the command line, plus a simple free Windows GUI.
Get it from the vendor
Ghostscript
Artifex Software
The engine behind many PDF tools: compress, convert to PDF/A, rasterise and repair PDFs from the command line.
Get it from the vendor
OCRmyPDF
OCRmyPDF project
Adds a searchable text layer to scanned PDFs — old reports, standards and drawings become searchable.
Get it from the vendor
PDFsam Basic
Sober Lemur
Split, merge, rotate and extract PDF pages — for drawing sets, specifications and submissions.
Get it from the vendorThe bottom line
qpdf is the quiet tool that rescues problem files and makes automation easy. Completely free, commercial work included.