AI chatbot ChatGPT has reached 100 million weekly active users, OpenAI CEO Sam Altman has announced, as he released new GPT-4 Turbo model that is more capable, cheaper and supports a 128K context window.

Addressing the company’s first developer conference here late on Monday, he said that the service, released nearly a year ago, garnered an estimated 100 million monthly users within just two months of launching.

Over two million developers use the platform, including more than 92 per cent of Fortune 500 companies, he told the developers.

GPT-4 Turbo has a 128k context window so it can fit the equivalent of more than 300 pages of text in a single prompt. 

“We also optimised its performance so we are able to offer GPT-4 Turbo at a 3x cheaper price for input tokens and a 2x cheaper price for output tokens compared to GPT-4,” said the company.

In addition to GPT-4 Turbo, the company is also releasing a new version of GPT-3.5 Turbo that supports a 16K context window by default.

OpenAI also released Assistants API to help developers build agent-like experiences within their own applications. 

“An assistant is a purpose-built AI that has specific instructions, leverages extra knowledge, and can call models and tools to perform tasks. The new Assistants API provides new capabilities such as Code Interpreter and Retrieval as well as function calling,” said the company.

OpenAI is introducing a text-to-speech API that offers six preset voices to choose from and two generative AI model variants.

Developers can now generate human-quality speech from text via the text-to-speech API. Pricing starts at $0.015 per input 1,000 characters.

Developers can also integrate DALL·E 3, which was recently launched to ChatGPT Plus and Enterprise users, directly into their apps and products, the company announced.