OpenAI has introduced GPT‑5.3-Codex, a new model that claims to enhance the coding performance of GPT‑5.2-Codex and the reasoning and professional knowledge capabilities of GPT‑5.2.
Claiming to be “the most capable agentic coding model to date”, it is 25% faster, enabling the execution of tasks involving research, tool use, and complex tasks.
“Much like a colleague, you can steer and interact with GPT‑5.3-Codex while it’s working, without losing context,” the announcement stated.
GPT‑5.3‑Codex
Being OpenAI’s first model, instrumental in its own creation, early versions helped debug its own training, manage its own deployment, and analyse test results and evaluations.
In four benchmarks measuring coding, agentic, and real-world skills, GPT‑5.3-Codex outperforms previous models on SWE-Bench Pro and Terminal-Bench, with strong results on OSWorld and GDPval.
In web development, it combines coding capabilities, improvements in aesthetics, and compact results. It claims to help build highly functional, complex games and apps from scratch in days.
Beyond coding, GPT-5.3 Codex also supports debugging, deployment, monitoring, writing PRDs, editing copy, user research, testing, metrics, and more.
“With the new model, Codex provides frequent updates so you stay appraised of key decisions and progress as it works. Instead of waiting for a final output, you can interact in real time—ask questions, discuss approaches, and steer toward the solution. GPT‑5.3-Codex talks through what it’s doing, responds to feedback, and keeps you in the loop from start to finish,” the announcement added.
GPT‑5.3-Codex is available with paid ChatGPT plans.
