PDF.js was originally created as aan [[Browser extension|extension]] for [[Firefox]]<ref name=":0">{{cite web|title = PDF Viewer(discontinued) |url = https://addons.mozilla.org/en-US/firefox/addon/pdfjs/|website = addons.mozilla.org |access-date = 2015-12-02 |url-status = dead |archive-url = https://web.archive.org/web/20151205121858/https://addons.mozilla.org/en-US/firefox/addon/pdfjs/|archive-date = 5 December 2015}}</ref> and is included in Firefox since 2012. (version 15),<ref>{{cite web |title=PDF.JS and Download Manager Panel Pushed to Firefox 15 |first=Lucian |last=Parfeni |url=https://news.softpedia.com/news/PDF-JS-and-Download-Manager-Panel-Pushed-to-Firefox-15-267154.shtml |website=[[Softpedia]] |publisher=SoftNews |date=2012-04-30}}</ref><ref>{{cite web |title = Вышла новая версия браузера Firefox 15 | first = Anton | last = Blagoveschenskiy | url = https://www.rg.ru/2012/08/29/firefox-site-anons.html | newspaper = [[Rossiyskaya Gazeta]] | date = 2012-08-29 | access-date = 2012-09-09 | language = ru |trans-title = New version 15 of the Firefox browser released }}</ref> and enabled by default since 2013 (version 19).<ref>{{cite web|url=https://bugzilla.mozilla.org/show_bug.cgi?id=773397|title=Bug 773397 – Disable pdf.js prior to FF15 beta 5|website=bugzilla.mozilla.org}}</ref><ref name="Firefox Notes - Desktop">{{cite web|title=Firefox 19.0 Release Notes|url=https://www.mozilla.org/en-US/firefox/19.0/releasenotes/|access-date=30 April 2013|website=mozilla.org}}</ref>
The project was created to provide a way for viewing PDF documents natively in the web browser, which prevents potential security risks when opening PDF documents outside a browser, as the code for displaying the document is [[sandboxed]] in a browser.<ref name=":2">{{Cite web |last=Shankland |first=Stephen |date=2011-06-24 |title=Mozilla eyes hassle-free PDFs on the Web |url=https://www.cnet.com/culture/mozilla-eyes-hassle-free-pdfs-on-the-web/ |access-date=2022-05-24 |website=CNET |language=en}}</ref> Its implementation uses the [[Canvas element]] from [[HTML5]], which allows for fast rendering speeds.<ref name=":2" />
