GPT-3 API is still the hardest single project I've worked on. Most common startup mistake is to start with a technology, rather than a user problem to solve — but working on one problem would sacrifice AGI focus. So felt like it probably wouldn't work, but had to push through.
Around this time 3 years ago, early 2020, we started testing the OpenAI GPT-3 API with the first external users. It was really hard to get anyone to try it, let alone build on it. So much has changed since then, but still feels like we're in the early days.