GoCo is described as 'A modern, all-in-one HR + benefits + payroll platform for small businesses'. There are three alternatives to GoCo for Online / Web-based, Self-Hosted solutions, SaaS, iPad and iPhone. The best alternative is PeopleKeep. It's not free, so if you're looking for a free alternative, you could try Grove HR.
PeopleKeep has created a new way to offer benefits called personalized benefits. For small businesses that think offering traditional group benefits sucks, PeopleKeep makes offering benefits simple, painless, and personal for everyone.