Structured Outputs with the OpenAI API
Learn how OpenAI structured outputs work, when to use JSON schema, how they differ from JSON mode and function calling, and how to design schemas safely.
Category API
OpenAI API guides — how to get an API key, pricing for every model, rate limits, fine-tuning, function calling, embeddings, Whisper, DALL-E, Sora, the Responses API, the Assistants API, and the Realtime API. Code samples and best practices.
OpenAI API Rate Limits: Tiers and How to Increase Them
Learn how OpenAI API rate limits work, what usage tiers mean, how to check your limits, and how to raise throughput without causing 429 errors.
OpenAI Token Counter: How to Count Tokens
Use this OpenAI token counter to estimate prompt size, plan API costs, avoid context-window errors, and choose tiktoken or API usage metadata.
Whisper API: Pricing and Code Samples
Whisper API pricing and code samples: speech-to-text model options, Python and JavaScript examples, timestamps, translations, and long-file tips.
OpenAI Assistants API: Build Your Own Agents
Learn what the OpenAI Assistants API does, how assistants, threads, messages, runs, tools, pricing, limits, and migration to Responses API fit together.
Free OpenAI API Key: Is It Possible in 2026?
Can you get a free OpenAI API key in 2026? Learn what is free, what requires billing, how credits work, and how to test the API safely on a small budget.