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PAGAI Tools
#1 in LLM APIs & inferenceUsage-based

OpenAI API

The default API for GPT models and OpenAI tools.

The OpenAI API, on platform.openai.com, is the developer platform for OpenAI models, including text, image, and tool-use APIs. You pay per token or per call. It is a different product from ChatGPT.

Official site

Why this rank

Most builder tutorials, SDKs, and examples assume this API. It is the first platform to wire up unless you already need a specific other model.

Best for

Shipping a feature on OpenAI models.

Pricing

Pay per token, with prices published per model on the OpenAI pricing page. Set a usage limit on the project before you put a key in an app. ChatGPT subscriptions do not pay this bill.

Pricing checked November 7, 2026. Confirm it on the official site.

Before you commit

  • A key in a client-side app will be stolen. Call the API from a server.
  • Spend follows traffic. A usage cap is part of the setup, not an extra.

Also look at

  • Claude Platform — Anthropic's API for Claude models.
  • OpenRouter — One API key for many models and providers.
  • Gemini API — Google's Gemini models, with a free tier in AI Studio.