Ask HN: Collecting leads from a landing page. Doing it yourself or use any app?

Hi, I want to ask you, do you use something to collect leads from your landin page or do you do it completely on your own by writing software? I'm asking because I'm thinking about creating a SaaS service that allows you to easily create and embed a form on a landing page. The collected information from customers would be in one place, you could filter it, send them emails with product updates.