Assalaamu alaykom wa rahmatullaahi wa barakaatuhu. I want to create a website for selling and buying, which needs a physical meeting with clients and sellers, and I have my sister to do this work. Is it halal or haram for my sister to meet strangers for work? May Allaah reward you.

All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.

It is better that you or a man that you authorize meets male clients and conducts the transactions of sales and purchases with them. If there is a valid need for assigning this task to your sister, then it is permissible on condition that there is no fear of Fitnah (temptation) and suspicions and that the Islamic etiquette governing the interactions of non-Mahram (permanently unmarriageable) men and women, such as avoiding being in seclusion with non-Mahram men, refraining from softening the voice, observing modesty, lowering the gaze, and confining the interactions to what is needed only, is observed. Please refer to fatwa 305425.

Allah knows best.