The Best Free & Open Source PDF Editors in 2021

pdf document

PDF files are everywhere. It's important to know how to edit and annotate them, especially if you're working with PDFs all the time. But editing a PDF file is not easy if you don't have the right software installed on your computer.

Free PDF editors are a great way to edit pdf documents without having to purchase expensive software, and they come with similar functionality. In this blog post, we will be going over the best open source pdf editors for various operating systems that can be used by anyone at any skill level with no cost or licensing restrictions.

Whether you're looking for alternatives to Adobe Acrobat or Javascript-based FOSS PDF editors to incorporate in your own web projects, there's something for everyone.

1. Okular

Free & Open Source | View & Annotate

The KDE community has created Okular, a global document reader. It runs on a variety of systems, including Windows, Mac OS X, Linux, and mobile. Okular's user interface is simplistic and minimalistic, and its ease of use serves to be one of its main advantages. it delivers everything a regular PDF reader generally does: the ability to make comments, text boxes, geometric shapes, lines, stamps, and highlight text through a simple and intuitive UI.

The full source code is available to view and contribute to on their GitLab.

2. PDF Sam Basic

Free & Open Source | View, Edit & Annotate

PDFSam Basic is a free and open-source application for organizing and managing PDF documents on Mac OS X, Windows, and Linux. What can PDFSam be used for? It's all in the name. PDFsam is primarily designed to split and merge PDF files. However, PDFsam comes in three separate editions, each with its own set of tools.

  • PDFsam Basic is a free and open-source utility for splitting, merging, rotating, extracting pages, and mixing PDF files.
  • Compress, crop, rotate, fix, encrypt & decrypt, erase pages, convert to PDF, extract text from pages, and more using PDFsam Visual.
  • View, convert, generate, edit, fill forms, OCR, sign, and more with PDFsam Enhanced. (The OCR component is only available in the Pro edition.)

PDF Sam Basic is free and open-source, with the source code available on GitHub.

3. Sejda PDF

Free & Open Source | View, Edit & Annotate

Sejda SDK is an open-source Java library that powers both PDF Sam and

Sejda is a PDF editor that is available in both free and premium editions, as well as online and desktop versions. The only difference between the online and offline versions is that the desktop edition does all of the processing locally rather than on the cloud, so your data never leaves your computer.

However, both the desktop and internet utilities' free versions have limits. You can only do three jobs per day, and you can only work on one document at a time. You can only work on files that are no more than 50MB or 200 pages.

You can find the complete source code on GitHub.

4. Sumatra PDF

Free & Open Source | View & Annotate | For Windows Only

With Sumatra PDF you can easily view and extract text from any format of your choice. This free PC software is powerful, small in size so it starts up very fast - perfect for those who always have something to do. The user interface has simplicity as its priority which leaves room only for features that are necessary or desired by users themselves!

The most recent update to Sumatra PDF promises a sleek and intuitive user interface. The software is small, portable with quick loading times which will make browsing books easier on your computer system as well!

Sumatra PDF is free and open-source, and the source code is available on GitHub.

5. Apache OpenOffice Draw

Free & Open Source | View, Edit & Annotate

Apache OpenOffice is a free and open-source productivity software suite that includes a wide variety of tools that allow users to perform actions such as word processing, spreadsheets, presentations, graphics, a formula editor, and database administration, all for free!

OpenOffice is multilingual, runs on all mainstream computers, saves data in ODF (the international open standard format), and can read and write files in a variety of different formats, including the format used by most office suite applications. OpenOffice can also export documents in PDF format.

The source code for the project is available on their website.

6. PDF.js

Free & Open Source | View Only

If you're looking for a Javascript-based open-source PDF viewer that you can incorporate into your own project, look no further than PDF.js. Developed by Mozilla, it is an open-source project that they use to power their own editor within the Firefox browser to view PDFs.

The source code is free to use and available on their GitHub.


Free & Open Source | View, Edit & Annotate

Built on top of Apache OpenOffice, LibreOffice has its own set of productivity suites that rivals the functionality of Microsoft 365. Free to use and completely open-source, LibreOffice includes a word processor called Writer; Calc is the spreadsheet application of choice when it comes to crunching numbers in your spreadsheets while Impress gives you presentations without having any need for PowerPoint files which tend not only to take up space but also use more processing power!

Draw allows users who are talented artists alike to create beautifully crafted drawings from scratch all within this free office suite - doodles have never been so easy before! And lastly, there's Basecamp where most people go if they want some serious database functionality at their disposal.

Their open-source PDF editor was created to be like Microsoft Word so that it can open and edit files easily. The editing of these documents is relatively easy - you just need the right tools for your needs! You will find all sorts of features in this free word processor, including adding text on top or redacting specific areas with ease.

The source code of the entire LibreOffice suite is free to use and distribute, and the source code is available here.