OpenAI on Wednesday released GPT-5.3-Codex, which the company calls its most capable coding agent to date, in an announcement timed to land at the exact same moment Anthropic unveiled its own flagship model upgrade, Claude Opus 4.6. The synchronized launches mark the opening salvo in what industry observers are calling the AI coding wars — a high-stakes battle to capture the enterprise software development market. The dueling announcements came amid an already heated week between the two AI giants, who are also set to air competing Super Bowl advertisements on Sunday, and whose executives have been trading barbs publicly over business models, access, and corporate ethics. “I love building with this model; it feels like more of a step forward than the benchmarks suggest,” OpenAI CEO Sam Altman wrote on X minutes after the launch. He later added: “It was amazing to watch how much faster we were able to ship 5.3-Codex by using 5.3-Codex, and for sure this is a sign of things to come.”

Full report : OpenAI’s GPT-5.3-Codex drops as Anthropic upgrades Claude — AI coding wars heat up ahead of Super Bowl ads.