PDF.js can work as a part of a website or of a browser. Originally created as a [[Firefox extension]],<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> it is [[List_of_Firefox_extensions#Included_in_Firefox|included in [[Mozilla 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 is 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> It is also included in [[ownCloud]],<ref>{{Citation|title=owncloud/files_pdfviewer|date=2020-02-08|url=https://github.com/owncloud/files_pdfviewer|publisher=ownCloud|access-date=2020-03-28}}</ref> [[Nextcloud]],<ref>{{Citation|title=nextcloud/files_pdfviewer|date=2020-03-18|url=https://github.com/nextcloud/files_pdfviewer|publisher=Nextcloud|access-date=2020-03-28}}</ref><ref>{{Cite web|url=https://apps.nextcloud.com/apps/files_pdfviewer|title=PDF viewer - Apps - App Store - Nextcloud|website=apps.nextcloud.com|access-date=2020-03-28}}</ref> and as a browser extension for [[Google Chrome]], [[Chromium (web browser)|Chromium]],<ref>{{cite web|url=https://chrome.google.com/webstore/detail/pdf-viewer/oemmndcbldboiebfnladdacbdfmadadm|title=PDF Viewer|website=Chrome Web Store}}</ref> [[Firefox for Android]],<ref>{{cite web|title=Android PDF.js|url=https://addons.mozilla.org/android/addon/android-pdf-js|website=addons.mozilla.org}}</ref> [[Pale Moon (web browser)|Pale Moon]]<ref>{{cite web|title=Add-ons - Moon PDF Viewer|url=https://addons.palemoon.org/addon/moon-pdf-viewer|url-status=dead|archive-url=https://web.archive.org/web/20200103222159/https://addons.palemoon.org/addon/moon-pdf-viewer/|archive-date=January 3, 2020|access-date=May 4, 2021|website=Pale Moon - Add-ons}}</ref><ref name=":1">{{Cite web|title=IsaacSchemm/pdf.js-seamonkey: SeaMonkey fork of pdf.js|url=https://github.com/IsaacSchemm/pdf.js-seamonkey|url-status=live|archive-url=https://web.archive.org/web/20201206160734/https://github.com/IsaacSchemm/pdf.js-seamonkey|archive-date=December 6, 2020|access-date=May 4, 2021|website=[[GitHub]]}}</ref> and [[SeaMonkey]].<ref name=":1" /><ref>{{cite web|title=PDF Viewer for SeaMonkey|url=https://addons.thunderbird.net/seamonkey/addon/pdf-js-for-seamonkey|website=Add-ons for SeaMonkey}}</ref>
Developers will also embed PDF.js in their software to enable PDF rendering and viewing in a web or native application or rendering on a server. Examples of PDF.js integrations include [[Dropbox (service)]] for PDF document previews,<ref>{{Cite web|last=Lauraharrisneal|title=Annotations on Document Previews|url=https://dropbox.tech/application/annotations-on-document-previews|access-date=2021-08-05|website=dropbox.tech|language=en}}</ref> [[Slack (software)]],<ref>{{Cite news|date=2016-11-16|title=What matters to you, matters to us. - Slack Engineering|language=en-US|work=Slack Engineering|url=https://slack.engineering/what-matters-to-you-matters-to-us-10ff49650a5d|access-date=2021-08-05}}</ref> and Linkedin for viewing accessible course materials online.<ref>{{Cite web|title=Under the hood: Learning with documents|url=https://engineering.linkedin.com/blog/2019/04/under-the-hood--learning-with-documents|access-date=2021-08-05|website=engineering.linkedin.com|language=en}}</ref> Some software development products are also making it easier to extend PDF.js.<ref>{{Cite web|title=Show HN: Pdf.js Express – PDF annotation, e-signatures, and form filling | Hacker News|url=https://news.ycombinator.com/item?id=22763656|access-date=2021-08-05|website=news.ycombinator.com}}</ref><ref>{{Cite web|title=Introducing PDF.js Express|url=https://pdfjs.express/_markdown_template/MarkdownTemplate|access-date=2021-08-05|website=pdfjs.express|language=en}}</ref>
