Codex growth and Claude Code's slowdown

OpenAI reduced API and credit pricing for GPT-5.6 Sol by more than 20% for three months, citing ongoing efficiency improvements. Credits purchased go further in Codex on token-based plans; subscription allowances are unchanged. OpenAI also added collaborative editing to ChatGPT Sites, letting multiple users co-build and publish while Codex handles git version control and continuous integration automatically. Codex holds 20 million weekly users, a level reached after GPT-5.6 launched on July 9, up from roughly 600,000 at the start of 2026. GPT-5.6 merged OpenAI's Codex and GPT-5 training stacks into a single system handling both frontier coding and general reasoning, and ships in three tiers: Sol for the hardest engineering tasks, Terra as the balanced default, and Luna for fast, low-cost use; Ultra mode enables four parallel sub-agents for Pro and Enterprise users. About 20% of Codex's user base is now knowledge workers, a segment growing three times faster than the developer base. Claude Code's monthly revenue growth has dropped to 5.2%, down from its prior hypergrowth pace, and the gap between Claude Code and Codex is described as having narrowed after Sol's release.