GPT-5.3 Codeex is OpenAI's newest coding model, released in February 2026. It's designed as a general-purpose "agentic" model, merging the strengths of previous GPT-5.2 models to handle end-to-end software engineering tasks. Sam Altman, founder of OpenAI, introduced GPT-5.3-Codex as a model with enhanced controllability and real-time update capabilities during task execution. GPT-5.3 Codeex is positioned as an interactive collaborator that can perform complex technical work. Early versions of GPT-5.3-Codex were used to debug its own training, manage deployment, and diagnose test results, making it the first model instrumental in its own creation.
Key features include acting as a general work agent, offering interactive real-time collaboration, and a focus on cybersecurity. It's optimized for speed, running 25% faster than its predecessor while using fewer tokens. GPT-5.3-Codex is classified as "High capability" for cybersecurity tasks, incorporating a comprehensive safety stack. The model has a context window of up to 400,000 tokens. GPT-5.3-Codex is available across all paid ChatGPT tiers in the app, via the CLI, via an IDE extension, and on the web. API access is planned to follow. Pricing starts at $1.75 per million input tokens and $14.00 per million output tokens. A lightweight version, GPT‑5.3‑Codex‑Spark, is designed for rapid inference and is available to ChatGPT's paid subscribers.
