OpenAI has launched GPT-5.3 Codex, a new model built to power its agentic coding tool Codex, turning it from a code-writing assistant into a broader digital worker capable of handling many tasks developers perform on a computer.
According to OpenAI, the model is 25% faster than GPT-5.2 and can build complex apps and games from scratch over several days. The company also noted that early versions of GPT-5.3 Codex were used internally to help debug and evaluate the model itself—making it the first OpenAI system that significantly contributed to its own development.
The release comes minutes after Anthropic dropped its own agentic coding model, in what turned into a closely watched timing race. Both companies had planned a 10 a.m. PST announcement, but Anthropic moved its launch 15 minutes earlier.
With GPT-5.3 Codex, OpenAI is positioning Codex as more than a coding assistant—framing it as a tool that could expand who can build software and how digital work gets done.
