You're looking for benefactors, not investors. An investment assumes a way to recoup the money.

An approach would be an NGO. Advertise the service and your vision and ask for donations to keep it going. You can also look for government grants related to unemployment. You could even ask the job seekers for a donation after they find a job.

Other than that, "dirty" monetization techniques are pretty much the only way to go. Ads, data selling, spam etc.