OpenAI

OpenAI is the company behind ChatGPT and the API platform that kicked off the modern wave of AI-powered software. Beyond the consumer chat product, OpenAI runs a developer platform where you send text (and images, audio, or files) to a hosted model and get a response back over HTTPS. You never download weights or manage GPUs — you authenticate with an API key, pick a model, and pay per token.

For a working developer, OpenAI matters because its API conventions became the de facto standard for the whole industry. The chat completions format — a list of messages with system, user, and assistant roles — is now mimicked by nearly every other provider and local inference tool, so learning it once transfers everywhere. Its docs and the OpenAI Cookbook are also some of the best worked examples of prompt engineering, structured outputs, and tool calling you’ll find, regardless of which vendor you eventually ship with.

In practice, you’ll create a key in the platform dashboard, install the official SDK (pip install openai or npm install openai), and make your first call in a few lines: instantiate a client, pass a model name and messages array, read the response. From there you’ll layer on streaming for responsive UIs, function calling so the model can trigger your code, and JSON-mode outputs your application can parse reliably. Treat this topic as learning the grammar most of the AI ecosystem speaks.