I am trying to find the Hansen solubility parameters for screening miscible substances. Could anyone suggest an open-source online tool to calculate the Hansen Solubility parameter or any other equivalent solubility parameters?
I'm not sure if there is such free tool. You've probably come across the 'hansen-solubility.com' website which provides a paid software named HSPiP (https://www.hansen-solubility.com/buy-HSPiP-software.php). There is also another site that shows a way to estime HSP values: https://www.pirika.com/ENG/HSP/E-Book/Chap30.html
Basf company seems to have an online tool that can calculate HSP as well. It is called Zoomlab.
I'm also looking for a free tool that makes the process easier, but I haven't found it.