PDF SDKs: Open Source vs. Proprietary | Guide Part 1

PDF SDKs: Open Source vs. Proprietary | Guide Part 1

The top 7 PDF SDK factors to consider. Should you go with an open source or a proprietary PDF Library? It’s not a simple decision, but this guide will help you to make it easier.

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PDF SDKs: How Do You Choose?

Are you looking for a PDF solution to help with your document management workflows? Maybe it’s an internal enterprise application, maybe it’s a PDF process embedded in a commercial product. 

Whatever your reason, if you need to convert, render, parse, extract, edit, compress, sign, or validate documents—you’ve got options.

One of the biggest decisions is between using Open Source versus Proprietary software.

In this guide, we’ll walk you through the choices, including the most important factors to consider when getting started. We’ll also provide a comparison of open source libraries versus proprietary PDF SDKs—including customization, security, reliability, support, cost, and more.

First, let’s start with basic definitions. 

What’s the Difference?

Open source software is freely available for anyone to use or modify. It’s distributed with its source code, so users can make and distribute changes according to its licensing agreement. 

Open source can be a good place for organizations to get started, especially if you only need simple PDF functionality and don’t have a big budget. PDFium and PDF.js are well-tested open source options for parsing and rendering PDFs. They’re distributed under MIT and Apache 2.0 licenses, respectively, making them popular with startups who need to add basic PDF viewing into a website or web app. 

Proprietary software is non-free software that is owned by the company or individual who created it. The source code is not publically available, and the use and modification of the code are limited by patent or licensing rights.

A proprietary PDF SDK includes a comprehensive development library that lets developers integrate PDF functionalities into in-house applications. The upfront cost is higher, but it comes with much more functionality and support than open source solutions.

Below we go deeper into a few key areas you should have top of mind when evaluating your options.

Top 7 PDF SDK factors to consider

Open source and proprietary solutions both have their advantages. But what you chose ultimately depends on how you and your organization weigh the following considerations:

  1. Cost

  2. Feature & Functionality 

  3. Customizability & Flexibility

  4. Performance & Reliability

  5. Community & Support

  6. Security

  7. Long-Term Viability

Let’s explore why experts think these matter the most. 

1. Cost

  • Open Source solutions are typically free to get started with. This reduces upfront costs, but additional costs required for customization, integration, and support can add up over time. 

  • Proprietary solutions involve licensing fees and ongoing costs, often including recurring monthly fees. The upfront costs can be substantially higher, but they usually come with  more advanced features and dedicated support.

Why it matters: If you’re on a tight budget and need to get started right away, open-source solutions can provide cost savings at the start. However, proprietary solutions might offer more comprehensive support and advanced features that could justify their cost for specific use cases.

2. Features & Functionality

  • Open Source libraries offer some useful features, but the depth and maturity of these features are often lacking. This may not be the best option if you need advanced functionalities like PDF linearization, cross-platform support, and the ability to apply advanced electronic signatures.

  • Proprietary solutions come with a comprehensive set of features that have been refined over time. They might even offer specialized tools for specific industries. For example, the PDF Tools SDK allows you to create and perform detailed validation of PDF/A documents, an industry standard for long-term document archiving.

Why it matters: If your business or application requires only basic PDF processing, open source options may be enough for you. But if you need specific functionalities or advanced features, you might find that proprietary solutions will get you up and running faster.

3. Customizability & Flexibility

  • Open Source projects give you full access to the source code, so your main limitation is your internal developer’s time and familiarity with the codebase. This gives you more control over the software's appearance and functionality.

  • Proprietary PDF SDKs will allow you to tweak certain parameters, but only within the limits predefined by the vendors. Specific customizations may require vendor support, which can lead to delays or increased costs, or they may not be on the vendor’s roadmap at all.

Why it matters: If you need a highly tailored experience—from specific features and integration with existing systems, to UI appearance—open source solutions provide more flexibility than proprietary solutions. On the other hand, proprietary SDKs are more likely to provide what you need out-of-the-box, including a user-friendly setup and extensive documentation.

4. Performance & Reliability 

  • Open Source SDKs vary widely in terms of performance. Some are well-optimized and efficient, but many underperform due to limitations of community-driven development.

  • Proprietary SDKs are optimized for fast rendering, high throughput, and efficient memory usage. Overall, they'll give you a more consistent, fast, and efficient experience. 

Why it matters: If you’re processing thousands, or millions, of documents, you need a PDF SDK that’s fast, optimizes resources efficiently, handles bulk processing—and does it all equally well on a wide range of platforms.

5. Community & Support

  • Open Source projects have active communities contributing to development, bug fixes, and improvements. But this isn’t paid support, and it’s never guaranteed that someone will be there to jump in when you need it.

  • Proprietary solutions should come with dedicated support paid to be there when you need them. You can also rely on regular updates, bug fixes, and feature enhancements. At PDF Tools, it’s the devs who help build the software—not just technically trained support staff—who are there to help you through any hurdle. 

Why it matters: The level of support you need depends on your organization's technical expertise. If you lack in-house expertise, proprietary solutions might be more reliable for ongoing maintenance and troubleshooting.

6. Security

  • Open Source solutions benefit from community scrutiny. This brings a lot of collective knowledge and enthusiasm to fix issues and address vulnerabilities. But although open source cares about security, it’s often not the number one priority.

  • Proprietary SDKs offer enhanced security and operate under strict industry compliance requirements. The longevity of a business requires deep commitment to best practices and industry standards, making security a top priority for vendors.

Why it matters: If you’re processing documents with sensitive, confidential, or personally identifying information, security must be top-of-mind. Open-source options provide transparency, but proprietary solutions might offer a more secure environment.

7. Long-Term Viability

  • Open Source PDF projects often start well, but are later under-serviced or abandoned if community support and developer interest wanes. As companies build out custom needs and more advanced features, increasing project scope can lead an initially cost-efficient project to incur huge costs later on.

  • Proprietary SDKs are heavily dependent on the company who builds them. Future features and functionality depend on the vendor's roadmap and business decisions. And if a company goes out of business, that may send you up shit creek.  

Why it matters: Whether you go with open source or proprietary SDKs, make sure the community or company has been around for a while, with a track record of weathering industry changes and challenges.

So, Which Should You Choose? 

Picking the right PDF SDK for your organization comes down to how you weigh the above factors. It’s not always a straightforward decision, but we hope this has been a useful guide.

Continue with part II of this guide where we compare the pros and cons - plus we give advice based on your needs!

If you think proprietary is the way to go, we’d love to help. PDF Tools makes a comprehensive PDF SDK that lets developers easily integrate advanced PDF functionalities into any document management workflow. And we’ve been doing this since Adobe gave birth to the PDF format in the 1990s. So we know how this works, and we’ll be around for the long haul. 

If you’re still unsure, we’d love to help too. We suggest you start with a deeper dive into the pros and cons of open source versus proprietary PDF SDKs. There, we map out the strengths and weaknesses of each option, along with a mini-guide for weighing the above factors. We also share some tips for making an informed decision—considering both current and future needs. 

If you’d like a more hands-on option, give our PDF SDK a test run—completely free with all the features. What better way to help you make the right decision?

Try Pdftools and see for yourself

Sign up for a free 30-day trial and join the 6,000+ customers already using Pdftools to manage their documents.

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