Probably the most famous job search engine is LinkedIn, but that doesn't mean it's the only one. It also doesn't mean it's the one that will stay on top forever--remember when Monster.com was the best place to find candidates and a job? (Full disclosure: I got a job through a résumé posted on Monster way back in 1999.)
LinkedIn is certainly valuable, but not everyone is on there, and the people who have the most sought-after skills may be tired of yet another in-mail from a recruiter who is likely to ghost candidates after begging them to consider working for this "dream" company.
Startups also have special needs that established businesses do not. When the company is only six weeks old, it's not exactly clear how the positions will grow and change, and it takes a certain type of flexibility to perform one of those roles.
So, if you're looking for other job search engines, here are a few you might try.
While this is a general-purpose job-hunting site, it advertises incessantly on podcasts. There are 62 million weekly podcast listeners in the U.S. That's a huge group of people who are told over and over again that if they need to hire, they should use ZipRecruiter. That type of advertising helps you bring in candidates without having to pay specifically for the advertising. It's not a bad place to start.
Niche job boards
This isn't one job board, but rather the concept of a job search engine. If you're looking for engineers, check out Engineering.com. Do you want a great PR person? Try Mediabistro. The Muse put together a list of niche job search sites that can get you started, but don't be afraid to simply Google the type of position you want to fill plus jobs to see what job search engines come up! That's what your potential targets are doing. See where they are landing.
This job site is dedicated to tech and startups, which means that AngelList will attract people who want the startup experience. This is important when you're searching for that next new hire--not everyone wants the roller coaster of startup life.
This isn't just about entry-level jobs--it's anything part time, remote, or contract. If your company plan is to offer flexibility, start by looking for people who want flexibility. If you can't afford to pay a full-time marketer, look on FlexJobs to find a part-time one. The part-time professional marketplace has tons of untapped labor. Women, especially, want part-time work, and this is a great place to find them.
Traditional job boards
My Inc. colleague Larry Kim recently listed his top 16 picks for job boards. All of these are good, but I want to point out two specifically. Facebook and Google. Facebook may not be the place you go to look for jobs, but it's where jobs can come looking for you. You can set criteria to target people with the skills you need--and in the proper location. Facebook got its hand slapped for allowing companies to set illegal criteria--such as age and race--so hopefully, that's not an issue anymore.
Google Jobs is awesome for job seekers--but you can't list your jobs there. It scrapes other websites and produce results. So, a reminder that your job postings need to say what they really are. Please don't label your head of HR as the Chief Happiness Officer, because people aren't Googling that. Marketing jobs should be labeled marketing and no "Chief Magic Maker." Think about how people will search for jobs and use those key words.