What it is

pdfcpu is a PDF processing library and command-line tool written in Go. It lives in the Go and Golang ecosystem, is distributed under the Apache-2.0 license, and is listed under Business Software in the Document Management and E-Signatures category. The project has existed for nine years, carries 8,835 stars and 628 forks, and lists 121 open issues. Its maintainer, Horst Rutter, is a member of the PDF Association, and the project documentation lives at pdfcpu.io. The GitHub topics attached to the repository are cli, go, golang, golang-library, pdf, pdf-files, and pdf-tools, which describes both halves of what the codebase offers: a library for Go programs and an executable for shell use.

The concrete problem it solves is that PDF work is normally split between closed desktop applications and narrowly scoped scripts. pdfcpu gathers the routine operations of PDF handling into one tool: validating a file against the specification, optimizing it, encrypting or decrypting it, splitting, trimming, merging, resizing and rotating pages, extracting and manipulating images, fonts and metadata, adding or removing stamps and watermarks, and managing attachments and portfolios. It supports PDF versions through PDF 2.0 (ISO 32000-2), so the toolchain targets the current standard rather than only legacy files. The same engine is reachable two ways, which means a Go service and a shell pipeline can apply identical processing without depending on different vendors.

Key capabilities

• Validates PDFs and reports on file structure, with PDF 2.0 validation support described as basic and continuously improving.
• Splits, trims, and merges documents, including booklet, n-up, cut, grid, poster, and ndown page assembly commands.
• Encrypts and decrypts PDFs, changes owner and user passwords, and sets permissions.
• Signs documents and validates signature integrity, reports signature evidence, and removes signatures.
• Extracts and manipulates images, fonts, metadata, keywords, properties, and bookmarks.
• Adds and removes stamps and watermarks, and resizes, rotates, crops, and zooms pages.
• Manages attachments and portfolios, plus annotations, forms, and viewer preferences.

Who uses it and how

• Shell and CI pipelines validate incoming PDFs before they enter a document workflow.
• Go services import the library to run the same operations in-process instead of shelling out.
• Teams merge, split, and trim batches of files during document assembly and prepress work.
• Administrators apply or strip encryption and set document permissions before distribution.
• Reviewers check signature integrity or remove signatures from files as part of intake.

Getting started

The README points to separate installation instructions for the command-line interface and the Go API at pdfcpu.io. The CLI is invoked as pdfcpu followed by a command, for example pdfcpu validate input.pdf or pdfcpu merge merged.pdf in1.pdf in2.pdf.

When to use it — and when not to

Self-hosters and Go developers get a permissively licensed tool covering most standard PDF operations without a commercial license. The stated weakness is validation depth for PDF 2.0, which the README calls basic and still improving, so strict conformance checking against the newest standard is not its strong point. With 121 open issues and an actively changing codebase, pinning a version and testing upgrades is sensible.

pdfcpu validate input.pdf

pdfcpu merge merged.pdf in1.pdf in2.pdf

pdfcpu validate -vv <file.pdf>