OpenAI has launched its much awaited new model of its AI system GPT‑5.

GPT‑5 is a unified system with a smart, efficient model that answers most questions, it said in a statement.

The latest model will be the new default in ChatGPT, replacing GPT‑4o, OpenAI o3, OpenAI o4-mini, GPT‑4.1, and GPT‑4.5 for signed-in users, it added.

The launch of GPT-5 comes after it was delayed earlier even as rival Elon Musk xAI introduced its own new version of Grok and Meta went on a hiring spree from rivals including OpenAI to beef up its superintelligence unit.

The Sam Altman-led company said that GPT-5 has made significant advances in reducing hallucinations, improving instruction following, and minimizing sycophancy.

It has also enhanced GPT-5's performance in three of ChatGPT’s most common uses -- writing, coding, and health, it added.

In terms of coding, GPT-5 shows particular improvements in complex front‑end generation and debugging larger repositories.

GPT‑5 is also its most capable writing collaborator yet and the best model yet for health-related questions, it said.

"Importantly, ChatGPT does not replace a medical professional—think of it as a partner to help you understand results," it noted.

Earlier this  week, OpenAI launched two open-weight AI reasoning models with similar capabilities to its o-series.