GPT-4 Arrives

By Satwik · March 28, 2026

OpenAI released GPT-4 in March 2023. It was a clear step up from its predecessor on reasoning, coding, and exam-style benchmarks, and it accepted image inputs alongside text, though the vision capability rolled out more slowly than the text interface. For many practitioners GPT-4 was the first model that felt reliable enough to build serious products on, and the wave of applications that followed defined the rest of the year.

The technical report was notable for what it withheld. Citing competitive and safety considerations, OpenAI declined to disclose architecture, parameter count, training data, or training compute. This marked a visible shift for a lab whose name still advertised openness, and it reframed frontier model documentation as a place where capability details are deliberately omitted while behavior and evaluation are foregrounded.

From a security perspective GPT-4 raised the stakes on every prior concern. Better reasoning means better assistance with dual-use tasks; better coding means more capable autonomous agents built on top; multimodality opens new prompt-injection surfaces through images. The model also exhibited the persistent frontier problems -- confident hallucination, jailbreak susceptibility, and sensitivity to prompt phrasing -- now embedded in a far more capable substrate. GPT-4 is the anchor point of the explosion: the moment a hosted frontier model became simultaneously the most useful tool many engineers had ever used and the most capable general-purpose system that defenders had to reason about. Everything downstream, from agent frameworks to red-team norms, is partly a response to what this release made possible.