Even in 2024, not all digital content plays together nicely. Below, Red Software founder, Chris Truxaw, discusses some of the past and current challenges of bringing PDF editing and form filling to the web.
Red Software was a pioneer in this space, bringing the first massively used online PDF editor to market in 2008. Their technology, RAD PDF, continues to power countless enterprises around the globe.
Here at Red Software, we proudly offer the best way for a web app to edit PDF documents in a browser, let’s dig into why that’s so difficult!
Three Decades of Digital Paper
PDF documents weren’t first created with the web we use today in mind. Adobe introduced the PDF specification in 1993, over 30 years ago. It was primarily a tool for reliably printing documents anywhere. Prior to PDF, printing on two different computers while maintaining consistent fonts and graphics was a near impossible task.
Today, the modern office rarely bothers to print a document, but document fidelity is more important than ever. Whether it is architectural plans, legal contracts, medical forms, or signed documents, PDF is still the goto digital paper format. But this document structure (and its uses) sharply contrasts with HTML and its structure which powers the modern web.
Most websites, even today, rely on simply hyperlinking to digital PDF documents – taking their user offsite. But many app creators and websites would strongly benefit by opening that document directly, without leaving the browser.
HTML vs COS – Two Document Approaches
Most technical folks are familiar with HTML (Hypertext Markup Language), the document structure which powers the web, describing how a web page looks and feels. But fewer have ever looked into the structure of a PDF. And for good reason, its contents can’t be read with a mere text viewer.
HTML is a relatively simple, text-based markup language which allows for content to be easily transmitted over the web. While it does allow for fonts and styles to be specified, there is no rigid layout in most cases. And is near impossible to print consistently across browsers and devices. This poses a significant problem for any data which is to be archived or is expected in a specific layout.
The COS (or “Carousel” Object System) organizes the bulk of the internal structure of a PDF. Named after Adobe’s codename for the project which would become Acrobat, COS offers a number of advantages over HTML like compression and binary data streams. These allow PDF files to contain not only a document’s structure, but also metadata and other resources like fonts and images, all in one compressible and portable envelope. Afterall, PDF is the Portable Document Format.
Because it is not text-based, PDF and its COS structure require special tools to properly inspect it. Internally, the COS organizes all the various attributes of a PDF (like page sizes, form field placement, annotations, and more). The actual page content of a PDF is largely represented in PostScript. The use of PostScript ensures consistent layout of content across devices; it has been used by printers since the 70’s. Unlike HTML, it contains binary data, complex structures, numerous data encodings, and may even be encrypted. Because of this, PDF documents have largely relied on readers outside of the web browser.
The resulting problem: an HTML document has no way to talk to a PDF, and a COS structure has no knowledge of a web page it may be displayed within!
Perhaps the day will come when the PDF and web standards communities fully embrace each other, creating a unified standard or protocol interoperation. But given their two vastly different approaches and goals, this seems unlikely.
Using .NET To Tie PDF and Web Together
Closing this gap has been the focus of RAD PDF for over 15 years now.
Using a .NET WebControl component like RAD PDF (www.radpdf.com) allows for seamless website and PDF integration. RAD PDF removes the client side complexity of HTML vs COS, allowing PDF data to be loaded, parsed, and accurately displayed directly in a web application in minutes. And best of all, it works in almost any browser! From Internet Explorer (yes you read that right) through the latest version of iOS, this approach delivers the consistency expected when utilizing PDF documents.
The .NET Framework / .NET Core / .NET 9 powers the backend of much of the web. That’s no different here. RAD PDF renders PDF files servers-side, sending them directly to the browser in a format easily consumed by almost any HTML web browser. This approach allows for the highest document fidelity across devices while also providing the web application full document control.
PDF files are feature rich and more advanced than just sheets of paper. Using RAD PDF, these expected features continue to be available (and disableable):
- Annotations & Markup – review and add new annotations, including embedded files
- Bookmarks & Thumbnails – navigate documents as the author intended and utilizing tables of contents
- Form Fields – fill PDF forms, utilizing built-in formatting and calculation scripts
- Sign & Certify – add digital signatures to documents
- Text Search & Selection – interact with text in a document, not just view it
With a comprehensive JavaScript API for HTML side integration, RAD PDF brings the most important data from a PDF’s complex COS structure directly to the browser. Modern web applications want to do more than simply link to a PDF form, they want to be able to display it, iterate through its fields, allow for signatures to be added, and more.
This approach allows for a number of exciting opportunities.
Content Protection Without Hassle
With a growing variety of user devices and screens, distributing and protecting the contents of a PDF document has never been trickier!
Many content protection schemes require the user to install an app, download specialized software, or to forego important features with clunky web viewers. Others only provide the illusion of protection, easily defeated by Developer Tools or crafty web requests.
RAD PDF presents a unique solution, by processing and rendering the document server-side, users continue to use familiar PDF document tools WITHOUT the PDF itself ever leaving your server.
Sharing a PDF document has advantages (like print fidelity and mass compatibility), but offers no protections against redistribution. With RAD PDF, you can maintain fidelity for users while retaining the original content safely within your firewalls.
Unlike many protection tools, RAD PDF works in just about ANY browser without requiring a user to install any software. In fact, RAD PDF’s compatibility is so broad it works seamlessly with the latest mobile and touch devices (including common features like pinch to zoom) while gracefully degrading to work with outdated browsers like Internet Explorer (6+).
With fine grained integration, RAD PDF allows your application to control user behavior authorizing every page view, print, content search, and more.
Digital Signatures Anywhere
Integrating a PDF file directly with a web application allows for the easy collection of digital signatures from just about any device. RAD PDF includes tools for both designating PDF signature locations and easy browser based PDF signing.
When a PDF document leaves your server, you lose control over how someone decides to sign that document. Some users may print, sign, and scan.
Others might digitally manipulate the file. Using RAD PDF, web applications can implement their own document signing workflow, allowing a user to quickly adopt and apply an electronic signature.
This PDF web control includes support for drawn, typed, or image based signatures. With RAD PDF, apps can customize the user signing experience and capture e-signed documents.
Form Data Collection Using Legacy PDFs
Most websites merely link to a PDF document, which the user then prints. With RAD PDF, data entered into a PDF form can be directly captured by a web application. Integrate designed and approved forms by directly loading existing PDF files with RAD PDF; saving redesign efforts. Then, because the user remains in your web application, extract user input, merge customer data, sign legal documents, and more with your own ASP.NET implementation.
Unlike a hyperlink, using RAD PDF’s ASP.NET web control instantly provides access to PDF form fields and their contents. For example, use JavaScript or C# logic to validate PDF field values, and prevent incomplete submissions.
Bridging the HTML – PDF gap not only allows web applications to go beyond static documents and readers, but also facilitates rich apps which annotate, form fill, sign redact, and more with PDF content.
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