Most of the web applications require Digital Signing documents, files, eReturns (XML or JSON) etc, from user’s Browser using user’s local machine Key-store, USB Token or Smartcard. Older methods being java applets, Active X, etc which are phased out or are being phased out from the new Modern Browser offerings.
Recently much is being talked about WebCrypto API but as of now, WebCrypto API does not provide access to (Windows) or any other Key stores or local crypto USB/Smartcard device.
Also in most of the signing scenarios, for requirement to protect pdf file or data to be signed within the server boundaries, it’s not recommended to send complete pdf file or data to be signed, to web browser.
Developers and System Integrators please refer to below StackOverflow posts for more information: (Upvote if helpful !!)
For browser based signing scenarios, one such free Chrome extension available is Signer.Digital Chrome Extension. Local system (host running behind the chrome browser on windows) may be downloaded from: DOWNLOAD or from https://download.cnet.com/Signer-Digital-Chrome-Extension/3000-33362_4-78042540.html
Installing this host and restarting Chrome will automatically add Signer.Digital Chrome Extension
The actual working of this extension is illustrated here.
Signer.Digital Extension for Microsoft Edge Browser is under development and shall be available on Windows Store by mid of 2019.