Dec 25, 2025
OpenAI API Complete Guide: From Chat Completions to Assistants
The OpenAI API has become the foundation for countless AI applications, from chatbots to code assistants to creative tools. But with the rapid evolution of models—from GPT-4 to GPT-4 Turbo to the recent GPT-4o—and the introduction of the Assistants API, understanding the full landscape can be overwhelming. In this comprehensive guide, I’ll walk you through everything you need to build production…