Paragraph 13 from the Limited Source Code License for WebTWAINSDK
Limited support. The Licensee acknowledges that the Licensor is unable to provide effective support once the Licensee has modified the source code and /or created a product based on modified source code. Supporting and maintaining the modified source code is the responsibility of the Licensee. The Licensor will, however, provide advice insomuch as that is possible. It is the Licensee’s responsibility to fit, integrate and adapt any Software updates provided by the Licensor when purchasing a Limited Source Code License.
Further Information:

The Licensee shall receive all source code for the Software under the terms of a Limited Source Code Software License. The Limited use of the Software shall be for any Products developed by the Licensee for customers of the Licensee. Within the terms of the Limited Source Code License, the Licensee may modify the source code from the Software supplied hereunder or adapt or modify the Software in any way or use to create a derivative work.

If you are a developer and want to add TWAIN document scanning to your browser-based application and need maximum flexibility in designing, modifying and maintaining your solution, then the limited source code license is your best choice. You are able to change, modify or extend anything on what begins as a working solution for both Windows and macOS. You have all source code to debug if there is an issue. There is also ample sample documentation on our GitHub site to assist you including sample code for Vue, React, Angular and Blazor.