Open-source Adobe Acrobat alternatives

Stirling PDF is an open-source PDF editing platform that can run as a desktop app, in the browser, or on servers you control through a private API. The project's pitch is that documents can be edited, signed, redacted, converted and automated without being sent to an external service. It is written in Java and distributed with Docker for self-hosting.

It bundles more than 50 PDF tools, including merge, split, sign, redact, convert, OCR and compress. No-code pipelines in the interface let you automate repeated processing, and REST APIs cover nearly all tools for integration into existing systems. The interface is available in over 40 languages. Enterprise options include SSO, auditing and flexible on-premise deployments.

A quick start with Docker serves the app on a local port, and the documentation covers desktop and Kubernetes installs. The repository describes the project as open-core, and GitHub lists its license as 'Other', so confirm which features fall under which terms. It suits individuals and organizations that handle sensitive PDFs and prefer a self-hosted alternative to online PDF tools.

OCRmyPDF adds an optical character recognition text layer to scanned PDF files so they can be searched and copied from. It turns an ordinary PDF into a searchable PDF/A file and places the recognized text under the page image so copy and paste works accurately. The tool is written in Python and released under the MPL-2.0 license.

It uses the Tesseract OCR engine, which recognizes more than a hundred languages. The tool keeps the original image resolution, inserts OCR data without disturbing other content where possible, and can optimize images so output files are often smaller than the input. Optional deskewing and image cleaning run before recognition, input and output files are validated, and work is spread across available CPU cores. Processing happens on your own machine, which keeps documents private, and it is available from PyPI and Homebrew.

BentoPDF is a client-side PDF toolkit that handles files directly in the browser, so documents are never uploaded to a server. That design makes it attractive for sensitive paperwork, and it can also be self-hosted. You can merge, split and reorganize pages, edit and modify PDFs, convert images and other formats to PDF, convert PDFs to other formats, and secure or optimize files.

Deployment is flexible. The project documents static hosting, local self-hosting, Docker Compose and Podman, a Podman Quadlet setup and a simple self-hosted build mode, along with options for custom branding, disabling specific tools and removing the GitHub star counter. It also covers WebAssembly configuration, air-gapped or offline deployment, a CORS proxy for digital signatures, and version management. A commercial build is mentioned, and the interface is translated into multiple languages.

BentoPDF is licensed under AGPL-3.0, with commercial licensing noted in the documentation, and it is written in JavaScript and TypeScript. It suits individuals, teams and organizations that need a free alternative to online PDF tools without sending files to third parties.

Sioyek is a PDF viewer with a focus on textbooks and research papers. It is meant for people who read long technical documents and need to move around them quickly, rather than just scroll through pages.

Features documented in the README include quick open, which lets you search for and open any file you have previously used, and navigation through a document's table of contents. The project offers official documentation and a video overview. Installers cover Windows, macOS and Linux, a Homebrew cask is available, and third-party packages exist for Flathub, Alpine, Arch, Debian, NixOS, openSUSE and Ubuntu.

Sioyek is written in C and C++ with Qt and released under GPL-3.0. Building the development branch needs Qt 6.7 or 6.8, and the FAQ explains how to get past the macOS quarantine message. The author accepts support through a buy-me-a-coffee link.

PDFsam, short for PDF Split And Merge, is a desktop application for working with PDF files. PDFsam Basic, the free and open-source edition developed in this repository, extracts pages, splits, merges, mixes and rotates documents on multiple platforms.

The application is written with JavaFX. Since version 4 it is released as a self-contained application that bundles a jlinked JDK, whereas version 3 required a Java Runtime Environment 8 with JavaFX installed. Documentation, an FAQ, build instructions, contribution guidelines, a translation project and a list of properties and arguments to tweak behavior are all linked from the repository.

Since version 3, PDFsam Basic is licensed under the GNU Affero General Public License, while earlier versions were released under GPLv2. The software runs locally on your computer, so documents do not need to be uploaded to a web service.