Generally referrals from existing engineers is the most common.

Outside of that I have seen a couple of stealth startups create a separate corporation and use it to recruit people. In some cases there are some advantages to having a separate corp to employ people and have its sole client be the stealth startup.

EDIT: Fixed some grammar.

Hire a 3rd party headhunter on a project retainer. A seasoned search guy will have the ability to connect with the right level talent quickly. He should also have the business acumen and diplomatic skills to insure confidentiality. Serious candidate conversations covered with a mutual NDA.

Hey,

I'm an Associate consultant at VenturePact - a New York-based, invite-only marketplace that connects companies with pre-screened developers and designers based on their specific needs. I would be happy to help you find the developers which fit your budget and location to help you execute your requirements. Plus, our development partners pay us to be part of our network - so we won't charge you anything.

Please let me know if you have any questions. Really looking forward to hearing from you. :)

Have you considered, you know, to stop the stealth mode bullshit?

I mean, really?

It's just like any other kind of recruiting except you don't state anything about the product or company you are uncomfortable about, only the technology. Early stage startups have a much harder time recruiting experienced developers/engineers, so aim for junior/mid-level or just outsource it.

To recruit rather than outsource, and do it for free:

1. Use word of mouth referrals.

2. Network with others in local tech gatherings. Sites like meetup.com and your local entrepreneurial support groups are good places to start.

3. Browse around and contact directly via linkedin.

4. Post onto mailing lists via meetup.com, google groups, etc. for lists that allow job postings. Be sure to follow all the rules.

To recruit when you have cash to spend, in addition to above methods- first create a good site with a careeers section. You don't need to say anything about the product but you need presence to show validity and seriousness. Then:

1. Post job on sites that focus on startups like HN and http://careers.stackoverflow.com/ or post job on sites that manage resumes for you and also post to http://indeed.com/ like https://www.workable.com

2. Use recruiters/head hunters.

However, the fastest way to get started is to either:

1. Spec it out, learn to develop it yourself, and set it up. It will probably be terrible if you don't know what you are doing, but you'll thank yourself that you tried later, if for no other reason than you better appreciate the engineer and what skills are necessary. Don't assume you hack-ass project will be sustainable though and it may even detract developers/engineers from coming aboard. But if you have something, that's better than nothing.

2. Farm it out. Outsource development and hope what you get in return is not really terrible. Bet on it being terrible though, and expensive.