OpenAI unveiled GPT-4 Turbo and introduced a GPT app store at its first-ever developer conference. The much-hyped DevDay event, held today in San Francisco, attracted close to 1,000 developers, who came together "to explore tools and exchange ideas." - GPT-4 Turbo, now in API preview, is trained with data up to April 2023, an advancement over the earlier GPT-4, which used data only up to September 2021. - Turbo's expanded 128K context window — equivalent to a 300-page book — allows it to comprehend longer inputs compared to earlier versions with context windows of 8K and 32K. - The input cost for Turbo is $0.01 per 1,000 tokens, less than the $0.03 charged for GPT-4. - OpenAI also announced a personalized chatbot builder for individual ChatGPT users. - Users can create custom chatbots, called "GPTs," for their own purposes or to share with others. - Alongside the builder, OpenAI is introducing a GPT Store or marketplace for users to post personalized AI chatbots for public download. - Eventually, users will be able to earn money from their apps based on usage statistics, according to OpenAI.