OpenAI

OpenAI is an AI research and product company that builds the GPT family of models and the ChatGPT assistant. It was founded in December 2015 as a nonprofit and is now organized as OpenAI Group PBC, a public benefit corporation controlled by the nonprofit OpenAI Foundation.

The structure changed in stages. OpenAI created a capped-profit subsidiary in 2019 to raise money for compute, then completed a recapitalization on October 28, 2025: the nonprofit became the OpenAI Foundation with a 26% equity stake and control of the board, and Microsoft took roughly 27%. On March 31, 2026, OpenAI said it had closed a $122 billion funding round at an $852 billion post-money valuation, anchored by Amazon, NVIDIA and SoftBank.

ChatGPT is the product most people know. At DevDay on September 29, 2026, OpenAI said ChatGPT had 1.2 billion weekly users, up from the 1 billion milestone it passed in July. Plans run from Free and Go through Plus, Pro, Business and Enterprise. Beyond chat, OpenAI ships Codex for software work, the ChatGPT Atlas browser, background agents called Dots announced at DevDay 2026, voice models under the GPT-Live name, and an API used by developers and enterprises. It also released gpt-oss-120b and gpt-oss-20b in August 2025, its first open-weight language models since GPT-2.

The model lineup turned over quickly in 2026. The GPT-5.6 family (Sol, Terra and Luna) became generally available in July. GPT-6 Astra, which OpenAI calls its most capable model, began rolling out on September 3, followed by GPT-6 Sol and Luna on September 22 and GPT-6.1 Sol at DevDay, which OpenAI says offers near-Astra performance at a fifth of Astra's API price. On October 7, OpenAI moved the main ChatGPT chat experience to GPT-6, with GPT-6 Sol for paid plans and GPT-6 Luna for Free and Go users, and added Intelligent UI, which lets answers include interactive charts, forms and tools. The names o3, o4-mini and GPT-4o that dominated 2025 coverage are now legacy.

For AI visibility, OpenAI matters because of reach and because of how ChatGPT finds sources. When ChatGPT searches the web it rewrites the user's prompt into one or more search queries, retrieves pages and cites some of them inline. OpenAI says GPT-6 makes better decisions about when to search and that GPT-6 Instant starts answering web-search questions 44% sooner than GPT-5.6 Instant, so search behavior keeps shifting with each model release. Our analysis of how ChatGPT searches the web covers the mechanics, and the top ChatGPT citations by domain show which sites it relies on.

Three practical points follow. First, access: OpenAI runs separate crawlers for training (GPTBot), search indexing (OAI-SearchBot) and user-initiated fetches (ChatGPT-User), and blocking the wrong one in robots.txt can remove a site from ChatGPT search results. Second, measurement: answers differ by model, plan and location, and the ChatGPT interface can differ from the API, so tracking should sample the real product across a fixed set of prompts. Third, query fan-out: because ChatGPT turns prompts into its own search queries, content needs to answer the sub-questions it generates, not only the head term. OpenAI's models also run inside third-party apps through the API, but those deployments rarely cite the open web unless the developer adds a search tool.