What Is the OpenAI API?

The OpenAI API provides programmatic access to OpenAI’s models — including GPT-6 Astra, the GPT-5.6 family, GPT-Image-2, and the GPT-Realtime audio models. Unlike ChatGPT (the consumer product), the API lets developers and power users integrate these models into their own applications.

API vs. ChatGPT

Feature	ChatGPT	OpenAI API
Interface	Web/mobile app	HTTP API
Pricing	Monthly subscription tiers	Pay per token
Customization	Limited	Full (temperature, system prompts, tools)
Models	Curated selection	Full model lineup
Data usage	May train on conversations	Not used for training

Current Models

Model	Best For
GPT-6 Astra	The hardest end-to-end work — 1.05M token context, selectable reasoning levels
GPT-5.6 Sol	Professional work at lower cost than Astra
GPT-5.6 Terra	Balancing intelligence and cost for everyday tasks
GPT-5.6 Luna	High-volume, cost-sensitive workloads
GPT-Image-2	Image generation
GPT-Realtime / GPT-Transcribe	Speech-to-speech and transcription

Getting Started

Create an account at platform.openai.com
Generate an API key
Add billing (pay-as-you-go)
Start making requests

Pricing

Per 1M tokens, as of September 2026:

Model	Input	Cached input	Output
GPT-6 Astra	$10.00	$1.00	$50.00
GPT-5.6 Sol	$4.00	$0.40	$20.00
GPT-5.6 Terra	$2.00	$0.20	$12.00
GPT-5.6 Luna	$0.20	$0.02	$1.20

Two discounts are worth knowing about. Cached input costs 90% less than standard input, so repeated system prompts and long shared context get substantially cheaper. The Batch API halves every rate for work that can tolerate delayed results.

Sol’s rate is promotional at least through November 21, 2026, and long-context requests bill at higher rates. Check OpenAI’s pricing page for current figures.

A typical conversation costs fractions of a cent on the lower tiers — far cheaper than a monthly subscription for light-to-moderate use.

OpenAI API in Elvean

Elvean connects to the OpenAI API with your own key — no subscription needed. You get access to all OpenAI models plus the ability to use them alongside Claude, Gemini, and local models in the same conversation.