At its first developer conference, OpenAI announced GPT-4 Turbo: a faster, cheaper GPT-4 with a 128K-token context window — roughly 300 pages of text — and knowledge updated to April 2023. API pricing dropped significantly, a direct response to developer complaints about GPT-4's cost.

DevDay also introduced GPTs — custom chatbots anyone could build without code — and the GPT Store concept. The message was clear: OpenAI wanted an app ecosystem on top of its models, not just a chatbot.

The event was overshadowed days later by the board's brief firing of Sam Altman, but GPT-4 Turbo itself became the workhorse model of the GPT-4 era, powering ChatGPT Plus for over a year.