OpenAI is the maker of ChatGPT and the GPT model family, serving roughly 900M weekly active users with 50M+ paid subscribers — it filed its S-1 on June 8, 2026 ahead of a planned IPO.

Together AI is an open-source AI cloud (neocloud) for training and inference that crossed roughly $1B in annualized revenue and raised $800M at an $8.3B valuation in July 2026.