Unfortunately, I have no API or plugin access, but I've experimented a lot with ChatGPT-4 (you know, the paid version, do not confuse it with GPT-3.5 which you get in the free version). Contrary to many comments here, I'm pretty much convinced GPT-4 is technically ready to replace just about any software development business with a single person that's really good at writing prompts.
Now, I'm not going to convince you of that, but let me address one thing that I think is important.
Most of the comments here state that they usually just see simple examples and that the code it produces tends to be of junior level. Now, obviously, that is true but the thing here is that GPT-4 has a linear process of reasoning. It always sends you the very first draft and this confuses people because it is of a quality a human would never produce without planning and proofreading and therefore you'd intuitively expect it to have done exactly that. But is hasn't; for example, if it writes code for you, it will have to get any import statements or class member variables just right at the beginning. There's no adding an import when you need it when writing a method, which is what your average human would do. Considering that, GPT-4 is already well beyond human-level.
So to get GPT-4 to give better results, there are broadly 3 techniques I've found to work well and they all revolve around dealing with the linear reasoning thing.
1. Take it one step at a time, just like humans would. First have it get the big picture and then slowly drill down. Start with architecture and go on with high-level design, API design, test strategy before you tell it to start coding.
2. Prime it well. Tell it what it is (e.g. a senior software architect), tell it to ask for clarification when things are unclear, tell it things you might accidentally take for granted like coding style, approach to logging, naming conventions and doing test-driven development. Tell it to always inform you of potential improvements to previous work.
3. Continuously encourage it to improve on what is has done. Ask it to refactor the architecture a bit before starting on the design. And after it is done with the design, ask it whether it sees possible improvements to the architecture.
Now, obviously, that's a lot of work, but GPT-4 can do it all for you. Unfortunately, without API access or IDE integration, it's mostly a matter of copying and pasting between conversations, but by simply doing that you can easily get one instance of GPT-4 to play the manager and the reviewer and have the other one do the work. The results will blow you away. The speed won't, though (and that's probably why it's going to be a while before it will take over your average business).