I see variations on this thread just about every day on FD. Someone has a Big Idea, that just needs a little bit of engineering to show everyone how great it's going to be. But there is no money, so maybe a Tech Cofounder is the best path.
A couple of thoughts:
1. Do you really need a technical implementation to get to your next step?
What is your next step? Are you trying to get funding from someone? F&F? Angel(s)? VC? Are you trying to validate the idea with prospects? Doing some price sensitivity testing? Do any of these audiences really need to see what limited implementation you could put together yourself? Or would a prototype put together in Powerpoint / Presi / Balsamiq / Axure / UXPin get the job done at much less cost? Unless your Big Idea needs to prove that it can actually be built, a tech POC is possibly not useful.
2. What sort of person is likely to want to work for no cash?
The idea of a Tech Cofounder is that someone is going to like your idea so much, and believe in your ability to execute so much, that they are going to be willing to jump on board with you for no money up front. There are only two people this could be: 1) someone with deep tech skills who has already been through a successful venture and is now independently wealthy enough to invest in your Big Idea by trading time for equity, or 2) someone who lives with their parents and can't find any other work. The first guy already has a great network, access to other Big Ideas, probably some Big ideas of his own, and already knows how hard the execution of a Big Idea actually is, the second guy is useless to you.
3. A Tech Cofounder is unlikely to be useful
A co founder should be someone who is going to help you lead and evolve and prove the business model, not just write some code. A real cofounder is pretty much going to want to hire a bunch of people with the various specific skill sets to build out the entire stack, from UI, to the services layer, the the back end. And, you're probably building a cloud app, and so you need CloudOps/DevOps to keep the whole thing running and make sure it doesn't fall over in the middle of presenting your Big Idea. Really, nobody has that complete skill set with any depth. So, the Tech Cofounder doesn't actually solve your problem.
If your Big Idea has merit, it will show in your non-functional prototype testing, and someone will get so excited about the user/buyer feedback you've received that they will give you money to hire good talent.
So, now that I've talked you out of finding free tech talent, let's talk about what you really need. And the good news is that it is easily found for free. You need an Interaction Designer. This is the partner to your Big Idea. This is the person who will get your prototype both designed and built, and validated, and will help you evolve it based on feedback from prospects and investors. And, there are a ton of them out there now, fresh out of school, and looking for work. And, they are not finding jobs because they don't have a portfolio of "real" work. See where I'm going?