How to choose an open source Web PDF viewer?


The most basic function of the paper reading website is a Web PDF viewer, which can realize multi-system reading and multi-terminal reading with cloud storage. Through this post, you will know : ① What are the popular browser PDF viewer? ② What is PDF.js?  ③Why choose to use PDF.js?

Keywords: Web , PDF viewer, PDF.js , open source



PDF.js is a Portable Document Format (PDF) viewer that is built with HTML5.  PDF.js is community-driven and supported by Mozilla. Their goal is to create a general-purpose, web standards-based platform for parsing and rendering PDFs.

The project address of the PDF.js project on has obtained 38.7k stared, and it is the most popular pdf viewer solution in the world, and the project is still continuously updated, many people in the github project are contributing, which is worth following.

PDF.js Github


The functions of PDF.js in PDF viewer are very complete, including bookmarks, zooming documents, turning pages, querying, rotating pages, opening files, downloading files, printing files, etc. The online demo address is  https://

It can be said that PDF.js has almost the same functions and experience as the desktop side in PDF view. However, because Mozilla’s main purpose is to create a pdf viewer, PDF.js does not support adding annotations and editing PDF.  So,  many people  looks for a PDF.js version that can add annotations. I’m working on that version and I’ll post it on Github and blog about it later.

PDF.js view PDF



There are many commercial PDF viewer with basically the same functions and features. Here we take WebViewer as an example. The image below is a screenshot of the WebViewer demo.

WebViewer demo


In addition to the almost perfect experience of PDF.js in PDF viewing, WebViewer also has functions such as adding and editing annotations, editing PDF documents, etc., covering the entire PDF document processing functions, very powerful.

WebViewer have divided into pro and free versions. The free version (demo: will add a “PDFTRON” watermark to each page of the document after opening. The watermark can only be removed after upgrading to the pro version. The process of upgrading is complicated. You need to commit your connect information and wait for their customer service to negotiate the price. Because the complicated process and the estimated cost is not cheap, I gave up upgrading to the pro version.

And because the PDF document saved after being opened by WebViewer is forced to carry the “PDFTRON” watermark, which affects the document structure and breaks the viewing experience, so I also gave up the free version.

WebViewer watermark


Generally speaking, the free PDF viewer solutions basically use PDF.js. Although the functions of the commercial solutions are much more powerful, the fees are not cheap. As the most popular open source PDF viewer project, PDF.js has complete project documentation and an active community. For people like me who do not have much budget and are engaged in development for the purpose of exercising development capabilities, PDF.js is the best choice.

I chose PDF.js, and I recommend you to choose PDF.js. Think how cool it would be for us to optimize PDF.js and contribute to the PDF.js community.

For how to import PDF.js, please read the related article.

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