How different is PDF Shelter from other tools?
Usually, online PDF processing works in three steps:
- Files are uploaded to a remote server;
- they are processed (merged, converted, split, etc) on that remote machine;
- results are finally downloaded to your computer.
Our tool eliminates steps (1) and (3) by allowing your browser to carry out all the work.
By doing so, our tool frequently allows tasks to be finished much faster, as you don't have to wait for files to be downloaded or uploaded.
Moreover, since we don't have to maintain any server infrastructure for processing files from your side, we don't need to put any limits on free operations as other tools do. This greatly reduces costs for us and enables us to fulfill our vision of offering unlimited service without any cost for the user.
Finally, the fact that file upload avoidance is the cornerstone of how PDF Shelter operates ensures that your data is processed with maximum privacy, since nobody outside your browser (not even ourselves!) ever has any contact with your documents.
Why don't other tools do the same?
Web pages are mostly the combination of HTML, CSS, and JavaScript files. HTML files describe their content and structure, CSS defines their graphical layout, and JavaScript scripts describe how they should dynamically react to user interactions. Even though some static pages might have a very simple or even non-existent JavaScript component, JavaScript might be used for building very complex dynamic pages.
Established alternatives such as ILovePDF (which was created in 2010) or SmallPDF (2013) have been developed at a time when browsers, desktops, and mobile devices were much more limited than today. Rich dynamic web pages such as Google Docs and Google Calendar were just out of beta, and browsers were not so capable of running them smoothly as they do today.
In such a constrained scenario, building a reliable PDF conversion tool running exclusively on people's browsers would be very challenging. At the same time, cloud based PDF processing is much easier to implement - even if it brings higher maintenance costs - since cloud servers might be packed with a lot of dedicated CPU and memory resources and might benefit from a decades-old software ecosystem of command-line based PDF tools.
In fact, the two JavaScript libraries that PDF Shelter most strongly relies upon (PDF-LIB and pdf.js), were not available when ILovePDF came to the public. The first commit to the PDF-LIB public repo was made in May 7th, 2019, while the first version of pdf.js was released in July 2nd, 2011.
Finally, even though modern smartphones frequently feature more than 4GB of RAM and might even pack up to 11 billion transistors, some devices with little resources or in which browsers cannot be updated might not meet the minimum requirements to run tools like PDF Shelter. As a result, cloud-based tools are still useful as a fallback solution for these cases.
How does PDF Shelter use these open-source libraries?
PDF-LIB is a very capable JavaScript library allowing dynamic generation and modification of PDF files. All of our tools that generate PDF files out of any kind of input make use of this library.
Mozilla's pdf.js is a JavaScript library that was initially developed to enable PDF rendering from within Firefox without any external software or plugin. PDF Shelter makes use of this library for producing rasterized versions of PDF files that users might then download in standard image formats such as JPEG.
What browsers are currently supported?
Any version of Safari not earlier than 13.1, or any version of Chrome, Firefox, or Edge released after 2018 should be able to run PDF Shelter without problems.
What prevents older browsers from being supported?
Older browsers like Internet Explorer or Safari 12 might not pack the minimum functionality (adequate VM memory constraints, JIT performance, available APIs, etc) to smoothly run our tools.
