ChatGPT
AI AssistantOpenAI's conversational assistant. Plans are Free, Go, Plus, Pro, Business and Enterprise. GPT-6 Astra, released 3 September 2026, is reaching enterprises in OpenAI's Trusted Access Program first, with the API and the ChatGPT tiers following; the GPT-5.6 tiers (Luna, Sol) are what the plans have been serving.
How It Works
You type a message and the underlying GPT-5.6 model generates a reply one token (word-fragment) at a time, each token chosen based on the entire conversation so far. The same loop powers tool use: when a prompt needs live data, code execution or an image, the model decides to call the relevant tool (browsing, Code Interpreter, image generation) mid-reply and folds the result back into its answer. Conversation history is kept for the session so follow-up questions have context.
Free tier, plus Go / Plus / Pro paid tiers - see vendor pricing (varies by region)