GPT-4

Released March 14, 2023, GPT-4 was OpenAI's fourth-generation flagship and the model that defined the modern LLM era. It was the first widely deployed multimodal language model, accepting image inputs alongside text, and it passed a simulated bar exam in the top 10% of test takers — a leap from GPT-3.5's bottom-10% score. The default version shipped with an 8K context window, with a 32K variant available through the API.

GPT-4's technical details were never disclosed — OpenAI declined to reveal its parameter count or architecture — but its impact is undeniable: it powered the paid ChatGPT Plus tier, became the default enterprise LLM for two years, and spawned the GPT-4 Turbo (128K context, November 2023) and GPT-4V vision variants. It was removed from ChatGPT in 2025 but remains available through OpenAI's API. Access is API-only; no weights have ever been released.