OpenAI shut off API access to its Codex code models — code-davinci-002, code-davinci-001, code-cushman-002, and code-cushman-001 — having announced it three days earlier on 20 March. Users were pointed to GPT-3.5 Turbo, which OpenAI said was better at programming anyway. Codex had launched on the API in August 2021 and became the foundation of GitHub Copilot; it was retired without ever leaving its free limited beta. The sharpest objections came not from developers but from researchers, who pointed out that work built on Codex would no longer be reproducible. OpenAI replied that "Codex was free and in a limited beta, with heavy rate limits from the get go," but within days Sam Altman said the company had not realized how much people liked the model and would keep supporting it for researchers, and access continued through the Researcher Access Program. OpenAI announced ChatGPT plugins the same day.