Anthropic and OpenAI ship rival coding models minutes apart

Anthropic released Claude Opus 4.6 with agent teams in Claude Code and a 1 million-token context window in beta. OpenAI released GPT-5.3-Codex minutes later, reporting a 25% speed increase for Codex users.

Why it mattered The two companies had reportedly settled on the same release hour, and the near-simultaneous launches showed how closely each now tracks the other in agentic coding.

Corrections

2026-09-26: Verified the Anthropic “Introducing Claude Opus 4.6” primary (agent teams, 1M-token context window in beta) against an archived copy; the OpenAI GPT-5.3-Codex primary URL resolves but its content is bot-walled, so the Codex launch details rest on the two TechCrunch reports. Entry published.