Being a developer for 15 years and a CIO of a startup I would say their are 2 sides to this. First you as the idea/business person have to find a developer/CTO that is willing to commit to your business and to usually work for equity in place of their hourly rate. The CTO/developer is trusting you as a business partner (sometimes even with zero sales) to sell and launch the product into the wild.
As a tech co-founder sometimes it is easy to be taken for granted. An idea without execution is just an idea. That goes for coding it as well as the business model execution and launching.
When trying to bring in a tech co-founder, respect them for their background but don't just look at them as a coder. As tech co-founders we don't ask the "business person" to prove they are worth it by making a sale or two before we work with them. We just have to trust them.
Another words, there is only one way to find out if it will work out and that is working together. You are not going to be able to understand his/her code most likely and shouldn't have to. I would start out with something to gain a little traction and see some results in a fairly short amount of time. Let the CTO help you figure out what that is. Don't come up with the most complex problem just to try and get these solved for free :)
Most developers are not going to be able to code the entire stack anyway and will have to lean on friends and contacts to help them out or seek out another tech person to help (bring into the company). Eventually a team will build out the product. The first CTO/developer should be doing anything and everything to get the MVP up and running and not code the monolithic entire webapp.
From my experience 1 developer is not enough even in a startup.
Here is how I would structure it:
I would have 2 developers. One as CTO and one as CIO or VP of Engineering or no title at all at this point.. Give them 20% each. Take 50% yourself and have 10% for equity pool.
If you have to bring in a CMO or whatever you could give them 15% - 20%.
When/if you get funding, everyone dilutes equally.
Setup a small piece for the developers to work on for 3 weeks. If they achieve it give them 5% equity immediately and then have them earn the 15% remaining over the next 3 years to vest increments monthly. The 5% will show them you are serious and they will be motivated to earn the remaining. I don't know any developer at my level that would take the 5% and run as the 15% of a company with a working MVP and some sort of client traction is where the most valuation would come in.
This is assuming you are doing 100% sweat equity. If you don't give any equity to motivate and say they have to earn all of it over a long period of time that would not work in my opinion as they are essentially doing this in lieu of their normal hourly rate. In my case that would be around $100/hr - $200/hr.
Hope this helps,