How would people trust you that you are after a serious project?
If you are seriously looking for testers or demo users for your project then you must give something to the users so that they know they are not throwing away their email addresses. There are no background about you, your team, road map.
OP has been inactive for about 6 months already, I don't believe he reads anything from here and it is possible that his service does not even work anymore. He posted a few posts here quoting a link to sign up for his service, I believe when he didn’t get enough response, he just gave up.
Don't fall on spammers like AmpSocial, he's just trolling.