Should you go with an open source or a proprietary PDF SDK library? 

The answer is… it’s not that simple. But we’re here to help.

Finding the right PDF SDK means understanding your options and your needs—now and in the future. Do you need to annotate, validate, or eSign PDFs? Do you have thousands of files to convert or compress? Will you need to archive documents with PDF/A compliance?

In this article, we outline the key benefits and drawbacks of both open source and proprietary PDF SDKs. We’ll also share key things that developers and organizations should consider, along with a mini-guide to help you weigh the different factors.

If you’re wondering what open source or proprietary PDF SDKs are, you should start here.

If you need a guide for making informed decisions—including the pros and cons of different PDF SDK engines—let’s start with open source. 

Open Source PDF Libraries: Pros & Cons

Open source libraries are free to use and give you full access to the code base. It can be a good option for some organizations, especially if you only need simple PDF functionality and you’re on a tight budget.

Should you go with open source? As you decide, keep these things in mind.

Advantages of Open Source PDF SDKs

• Flexible customization: Open source SDKs let you customize the code according to specific project requirements. This means in-house developers can add or modify features as needed.

• Cost-effective: Open source PDF SDKs are free to use, so you can get started without expensive licensing fees. This means big savings on initial development costs.

• Community support: Open source projects often have active developer communities that provide support through forums, documentation, and bug fixes. This is great for troubleshooting and getting advice when you get stuck.

Disadvantages of Open Source PDF SDKs

• Features limitations: Open source libraries typically have fewer features than proprietary PDF SDKs. As companies grow, this adds work for in-house developers, or forces a switch to a proprietary solution.

• Compatibility: Open source software may not be compatible with other software, especially proprietary products. And not all open source PDF libraries are available on all platforms.

• Security risks: Most open source projects have been rigorously tested. But there are no legal obligations for security, and vulnerabilities can still arise.

• Limited official support: Open source communities are incredibly insightful and helpful. But it’s not a dedicated support team waiting to jump in whenever you need help.

Proprietary PDF SDKs: Pros & Cons

Proprietary PDF SDKs provide a more comprehensive development library out of the box. This lets developers more easily integrate PDF functionalities into in-house applications or commercial products, but not without a cost. 

In many cases, the advantages and disadvantages of open source are the mirror opposite of those with open source software. Let’s break it down. 

Advantages of Proprietary PDF SDKs

• Enhanced functionality: Proprietary PDF SDKs provide advanced features that open-source options often lack—things like encryption, digital signatures, extraction and form-filling capabilities, control over color transformations and font substitutions, support for industry standards like PDF/A, and more.

• Dedicated technical support: With a proprietary SDK, you should have access to responsive technical support, ideally from the developers who built it.

• Regular updates and improvements: Companies offering proprietary SDKs invest into continuous development and updates—from features to security standards. This leads to a more reliable and stable product over time. 

• Greater security: With concerns over cyber threats at an all-time high, proprietary options can’t afford to skimp on security. Both private pressures and industry standards help reinforce excellent security practices.  

Disadvantages of Proprietary PDF SDKs

• Higher cost: Proprietary solutions have higher upfront and ongoing costs through licensing fees or subscription models. Expect initial sticker shock compared to open source alternatives. 

• Limited customization: Proprietary PDF SDKs often provide extensive functionality out-of-the-box. But if you need a highly specific customization, it may not be on the company’s roadmap.

• Vendor dependence: With a proprietary PDF SDK, you rely on the company for ongoing support and maintenance. So make sure you go with a vendor with a long history and proven track record to make sure they’ll be around in the long run.

Tips for Smart PDF SDK Decision-Making

So which option is better for you? There’s no right choice, and the decision you make comes down to how you weigh the above pros and cons. 

But we know that doesn’t make it easy. So here’s a few more tips to guide your decision.

Know your budget

What’s more important to protect: your cash flow or developer resources? Open source PDF SDKs are free to use, but building out the feature sets and functionality you need can end up incurring big costs through internal developer resources.

Proprietary options come with a steeper price tag, but offer more out of the box, with better support and documentation that can save you down the line. Make sure you consider both short- and long-term costs.

• If you’re on a tight budget or have enthusiastic open source developers → Open Source

• If you have budget to spend or constrained development resources → Proprietary

Identify your project requirements

What are your must-haves and nice-to-haves? An open source library like PDF.js might be enough if you only need to preview PDFs. But if you need full PDF functionality—like document conversion, manipulation, annotation, digital signatures, and additional security measures—you’ll save lots of time and headache by using a proprietary PDF SDK.

• If you only need simple functions like PDF rendering → Open Source

• If you need advanced features or efficient high volume throughput → Proprietary   

Support your devs

How familiar are you with PDF applications and implementation already? And how much support do you expect to need? Open source communities rely on voluntary developer contributions, so support can vary. Proprietary solutions offer dedicated technical support, so your issues and questions get prompt attention.

And don’t forget about documentation. Both types of PDF SDKs should offer thorough documentation, but make sure to evaluate the clarity and accuracy of support materials before choosing an SDK.

• If support is less important for you → Open Source

• If you need quick, on-call, expert troubleshooting → Proprietary   

In both cases, check the documentation provided before you commit.

Look long-term

Like any project, it’s important not to over-scope when you’re getting started. But deciding on your PDF SDK engine can have important implications down the road as company needs and desires expand. Here are a few final considerations to help future-proof your decision. 

Future features. A big mistake is to assume fixed features requirements, which rarely remains the case. More often, needs evolve over time as teams demand increasing functionality. Open source may provide more control over the customization of future feature needs. Proprietary is more likely to already offer what you need now and in the future. 

Updates. Proprietary providers release regular updates, whereas open source updates are more sporadic. If opting for open source, it’s especially important to consider how future updates may affect any customization you’ve done. 

Scalability and integration. Consider how easily a PDF SDK can integrate with your existing infrastructure and platforms, and how easily it scales with future document processing volumes.

Switch costs. Changing PDF SDKs down the line can be expensive. And it’s not just the cost of the software and maintenance—developers have to learn a new library, update documentation, and rework the backend. 

Vendor reputation. Whatever you choose, make sure the project or vendor has been around, and will be in the future. Going with a cheap or flashy solution won’t help if they’re gone when the economy slumps. Instead, look for established companies with positive reviews on their product's stability, security, and support. 

• If you’re confident that project requirements will remain stable and you don’t expect huge scaling → Open Source

• If you need faster time-to-market and expect to scale in the future → Proprietary

Okay, same question: which is better for you? Sorry, same answer: it depends how you weigh the above factors, now and in the future. But we hope this guide has helped you better understand what you should have in mind. 

If you want a deeper look, review these seven PDF SDK factors and why they matter.

We admit we’re biased—at PDF Tools, we make a comprehensive PDF SDK that makes it easy to integrate advanced PDF functionalities into any document management workflow. We’re happy to say we’ve been around over 20 years—and we’re not going anywhere but forward.

But regardless of the solution you end up choosing, please get in touch if you have any questions—we’d love to talk with you. And if you’d like to try out our PDF SDK—with full support and no strings attached—you can start now for free.