New York City, NYC NY
Justworks - <a href="http://www.justworks.com" >
We are building a platform for people to administer every part of their business, starting with payroll, benefits, compliance and tax filing.  We've also built out PTO tracking, some reporting/analytics features and a B2B payments feature.  We aren't just about payroll.
We are a PEO, which means we coemploy our customers employees (similar to Trinet/Ambrose or ADP Total Source, if you've ever heard of those).  Because of that we're able to do a lot of really cool things including offer health insurance at a massive discount.  We're growing very quickly (35-40% month over month) and just raised a $6mm series A from Thrive, Index, a few others[1].
We handle payments and lots of very sensitive information (bank numbers, social security numbers etc.) so we need people who are comfortable working in that environment.  Basically we're looking for senior level engineers to help build the foundation for a really awesome engineering org.  Please feel free to reach out to me if you have any questions (REDACTED_EMAIL).
[1] <a href="http://blogs.wsj.com/venturecapital/2014/10/09/justworks-raises-6-million-to-help-businesses-handle-employee-benefits/" >
Ask HN: Who is hiring? (December 2014)