Summary
On September 10, 2026, OpenAI launched its Agents API in public beta for all developers, built on the open-source Codex harness. The API handles session state, context compaction, crash recovery, and subagent coordination, so developers supply tools, instructions, and an execution environment while OpenAI manages the orchestration loop. There is no added API fee beyond model tokens and paid tools.
What changed
OpenAI released the Agents API in public beta, packaging the Codex harness as a managed service built from four objects: an Agent, an optional Environment sandbox, a durable Session, and streamed events; sessions can run code, edit files, search the web, apply skills, and split work across subagents.
Why it matters
It lowers the barrier to production agents by removing the orchestration plumbing most teams rebuild by hand, and intensifies competition among managed agent runtimes. Pricing at tokens-plus-tools with no platform fee pressures rival harness and agent-infrastructure vendors on cost.
Evidence excerpt
The Agents API is available in public beta to all developers and is powered by the open-source Codex harness; there are no additional fees beyond the tokens and tools your agents use.