What is the ruling on profits gained from registering people on a website via my referral link, and is my work in marketing and data collection for this website permissible (halal)?

It is permissible to profit from browsing websites, advertising for them, bringing in customers, or designing ads for them, provided that these websites publish permissible content and do not promote forbidden things, and the wage is known. This falls under the category of ju'alah (reward for a service) and brokerage. It is stipulated that forbidden tricks, such as using fake accounts or software to falsely claim commissions, must be avoided. Furthermore, it is not permissible to advertise anything that involves an evil, based on the words of Allah Almighty: (And cooperate in righteousness and piety, but do not cooperate in sin and aggression), and the words of the Prophet, peace and blessings be upon him: (Whoever calls to misguidance will bear a burden of sin equivalent to the sins of those who follow him).

As for providing people's emails and phone numbers to websites, it is conditional upon obtaining the permission of the owners of these emails and numbers.

There is no harm in network marketing as long as it does not require purchasing a product or paying fees under any pretext.