# FAQ **URL:** https://pdfjs.community/c/faq/9.md [Latest](https://pdfjs.community/latest.md) · [Categories](https://pdfjs.community/categories.md) · [Tags](https://pdfjs.community/tags.md) --- ## [What is PDF.js Express?](https://pdfjs.community/t/what-is-pdf-js-express/27)
**Author:** [@Logan](https://pdfjs.community/u/Logan)\ **Replies:** 5\ **Last updated:** [February 25, 2022, 4:15pm UTC](https://pdfjs.community/t/what-is-pdf-js-express/27 "2022-02-25T16:15:33Z")
PDF.js Express is a client side PDF Viewing library, wrapping the open source library PDF.js. It adds additional functionality to PDF.js, such as annotations, form filling, a fully open sourced, customizable UI, and eSi… --- ## [About the FAQ category](https://pdfjs.community/t/about-the-faq-category/26)
**Author:** [@Logan](https://pdfjs.community/u/Logan)\ **Replies:** 0
This category contains answers to commonly asked questions about PDF.js and PDF.js Express. If you have some information you think belongs in the FAQ, feel free to create a topic and a moderator will look at it! --- ## [Can a license key be used in more than one application?](https://pdfjs.community/t/can-a-license-key-be-used-in-more-than-one-application/929)
**Author:** [@talles.sanavria](https://pdfjs.community/u/talles.sanavria)\ **Replies:** 2\ **Last updated:** [February 26, 2023, 9:37am UTC](https://pdfjs.community/t/can-a-license-key-be-used-in-more-than-one-application/929 "2023-02-26T09:37:10Z")
Hello If we have more than one application can i use the same licence? Local domain and public domain. Thanks --- ## [Does PdfJS Express Viewer Supports IE11?](https://pdfjs.community/t/does-pdfjs-express-viewer-supports-ie11/1297)
**Author:** [@user51](https://pdfjs.community/u/user51)\ **Replies:** 2\ **Last updated:** [December 21, 2022, 1:53am UTC](https://pdfjs.community/t/does-pdfjs-express-viewer-supports-ie11/1297 "2022-12-21T01:53:06Z")
Is there a support for IE 11 in free version of PDF JS Express? --- ## [pdf-js-express utility api actions question](https://pdfjs.community/t/pdf-js-express-utility-api-actions-question/1863)
**Author:** [@leolin](https://pdfjs.community/u/leolin)\ **Replies:** 0\ **Last updated:** [July 12, 2022, 7:37pm UTC](https://pdfjs.community/t/pdf-js-express-utility-api-actions-question/1863 "2022-07-12T19:37:07Z")
0-500: $0 USD 501-5500: $49 USD 5501-10500: $98 USD I would like to ask, how to pay for more than 500 times $49 ? --- ## [Express License Attribution](https://pdfjs.community/t/express-license-attribution/1453)
**Author:** [@sean](https://pdfjs.community/u/sean)\ **Replies:** 0\ **Last updated:** [March 8, 2022, 5:01pm UTC](https://pdfjs.community/t/express-license-attribution/1453 "2022-03-08T17:01:20Z")
Hello, In reviewing the Express license I noticed that there is a section on Attribution requirements ATTRIBUTION NOTICE. You agree to include the following notice in any location where You have Your own proprietary… --- ## [Is it possible to purchase a client API key that works for multiple-domains?](https://pdfjs.community/t/is-it-possible-to-purchase-a-client-api-key-that-works-for-multiple-domains/57)
**Author:** [@phiveweeze-betas](https://pdfjs.community/u/phiveweeze-betas)\ **Replies:** 1\ **Last updated:** [June 8, 2020, 6:07pm UTC](https://pdfjs.community/t/is-it-possible-to-purchase-a-client-api-key-that-works-for-multiple-domains/57 "2020-06-08T18:07:41Z")
Our company allows customers to pick/use their own domain. I don’t see any mention on the purchase page about multiple-domain support using 1 key, is this something that you offer? --- ## [License Restriction ?](https://pdfjs.community/t/license-restriction/450)
**Author:** [@SAM-HIM](https://pdfjs.community/u/SAM-HIM)\ **Replies:** 3\ **Last updated:** [February 1, 2022, 3:37pm UTC](https://pdfjs.community/t/license-restriction/450 "2022-02-01T15:37:31Z")
Are there any limitations besides a single registered domain? Such as the number of concurrent users, type of end users , number of users ? --- ## [Migrating back and forth from PDF.JS Express to PDFTron WebViewer](https://pdfjs.community/t/migrating-back-and-forth-from-pdf-js-express-to-pdftron-webviewer/1344)
**Author:** [@inincic](https://pdfjs.community/u/inincic)\ **Replies:** 0\ **Last updated:** [February 1, 2022, 3:36pm UTC](https://pdfjs.community/t/migrating-back-and-forth-from-pdf-js-express-to-pdftron-webviewer/1344 "2022-02-01T15:36:45Z")
Migrating back and forth PDF.JS Express to PDFTron WebViewer is very simple (the core API is the exact same) as long as you restrict the app to a subset of functionality supported by Express. For details, please see: ht… --- ## [Possibility to remove page](https://pdfjs.community/t/possibility-to-remove-page/1325)
**Author:** [@user67](https://pdfjs.community/u/user67)\ **Replies:** 1\ **Last updated:** [January 24, 2022, 6:37pm UTC](https://pdfjs.community/t/possibility-to-remove-page/1325 "2022-01-24T18:37:44Z")
I am using the pdfexpress free version and I would like to know if the the removePages feature can be used on this package or is it available on the pdfjs express plus package. If so, is it possible to ask for a little … --- ## [What is the recommended way to import/export annotations in PDF.js Express?](https://pdfjs.community/t/what-is-the-recommended-way-to-import-export-annotations-in-pdf-js-express/39)
**Author:** [@Logan](https://pdfjs.community/u/Logan)\ **Replies:** 3\ **Last updated:** [September 8, 2021, 7:23pm UTC](https://pdfjs.community/t/what-is-the-recommended-way-to-import-export-annotations-in-pdf-js-express/39 "2021-09-08T19:23:47Z")
The recommended way to import/export anntotations are with the importAnnotations and exportAnnotations APIs. An overview on import/export can be found here. --- ## [Where can we find counting of the rest api calls?](https://pdfjs.community/t/where-can-we-find-counting-of-the-rest-api-calls/456)
**Author:** [@SunnyTokyo](https://pdfjs.community/u/SunnyTokyo)\ **Replies:** 2\ **Last updated:** [January 22, 2021, 4:58am UTC](https://pdfjs.community/t/where-can-we-find-counting-of-the-rest-api-calls/456 "2021-01-22T04:58:09Z")
Hi there. We just started using the rest apis. Where can we find how many api calls are made in the current month? Just wondered how we can check the API pricing ladder in https://pdfjs.express/documentation/utils/pricin… --- ## [Do you need remote internet access to use PDF.js Express?](https://pdfjs.community/t/do-you-need-remote-internet-access-to-use-pdf-js-express/261)
**Author:** [@Logan](https://pdfjs.community/u/Logan)\ **Replies:** 0\ **Last updated:** [September 16, 2020, 6:09pm UTC](https://pdfjs.community/t/do-you-need-remote-internet-access-to-use-pdf-js-express/261 "2020-09-16T18:09:37Z")
Yes. PDF.js calls home to an authentication server to verify your license key. If this request fails, PDF.JS Express will display a watermark, even if a valid key is entered. However, our sister product, PDFTron WebVie… --- ## [Is it possible to add annotations to a PDF with PDF.js Express?](https://pdfjs.community/t/is-it-possible-to-add-annotations-to-a-pdf-with-pdf-js-express/36)
**Author:** [@Jackie](https://pdfjs.community/u/Jackie)\ **Replies:** 0\ **Last updated:** [May 25, 2020, 10:40am UTC](https://pdfjs.community/t/is-it-possible-to-add-annotations-to-a-pdf-with-pdf-js-express/36 "2020-05-25T10:40:07Z")
Absolutely. PDF.js Express imports annotations into the viewer through XFDF data. They can be created by the user through the UI, or programmatically. Annotation data can be imported or saved to a server/database. To l… --- ## [Which browsers are supported by PDF.js Express?](https://pdfjs.community/t/which-browsers-are-supported-by-pdf-js-express/33)
**Author:** [@Jackie](https://pdfjs.community/u/Jackie)\ **Replies:** 0\ **Last updated:** [May 25, 2020, 9:21am UTC](https://pdfjs.community/t/which-browsers-are-supported-by-pdf-js-express/33 "2020-05-25T09:21:34Z")
PDF.js Express Web Viewer can be used with all major browsers. Browser Supported Versions Chrome All ✓ Firefox All ✓ Safari All ✓ Edge All ✓ Internet Explorer 11+ Android Chrome All ✓ Mobile Safari A… --- ## [Which file formats are supported by PDF.js Express?](https://pdfjs.community/t/which-file-formats-are-supported-by-pdf-js-express/34)
**Author:** [@Jackie](https://pdfjs.community/u/Jackie)\ **Replies:** 0\ **Last updated:** [May 25, 2020, 9:24am UTC](https://pdfjs.community/t/which-file-formats-are-supported-by-pdf-js-express/34 "2020-05-25T09:24:00Z")
PDF.js Express Web Viewer is built around the PDF.js project which currently only supports PDF documents based on the PDF32000 specification. Try out PDF.js Express for free! --- ## [Which frameworks are compatible with PDF.js Express?](https://pdfjs.community/t/which-frameworks-are-compatible-with-pdf-js-express/35)
**Author:** [@Jackie](https://pdfjs.community/u/Jackie)\ **Replies:** 0\ **Last updated:** [May 25, 2020, 9:34am UTC](https://pdfjs.community/t/which-frameworks-are-compatible-with-pdf-js-express/35 "2020-05-25T09:34:36Z")
PDF.js Express Web Viewer is compatible with any JavaScript framework because all it needs is a DOM element to place the document viewing component. Angular Cordova Electron React Svelte Vue Blazor TypeScript To learn…