Hi Vivek,
Well yes, its called OutSystems. You need to code it. So what did you try already to solve your problem?
Is there anything specific that you didn't get to work, or you don't know how to approach this problem?
Do you have the multi-select dropdown already working?
If you would share some more information that would be helpful, if you want to use a solution that someone else created, then a search on the Forge is a better place to go to.
Regards,
Daniel