What is OpenAI Agents?
Latest launch Open source
Summary
OpenAI's agent harness, shipped as a Python SDK update in April 2026 and as the hosted Agents API in September 2026.
- Category
- Agent infra
- Open source
- Yes
- Pricing
- SDK and Agents API use standard token and tool pricing. The Agents API has no additional fee.
- Links
- Website
Two filings share this hub.
OpenAI Agents SDK sandbox harness (April 15, 2026) is the library update: sandboxes, a workspace manifest, and filesystem tools, Python first.
OpenAI Agents API (September 10, 2026) is the hosted beta of the Codex harness, with an optional hosted sandbox and no extra fee beyond usage.
The SDK launch is marked open source because OpenAI publishes the SDK and describes the Codex harness as open source. The API itself is a service OpenAI operates.
OpenAI Agents alternatives
| Tool | License | Pricing note |
|---|---|---|
OpenAI AgentsThis pageOpenAI's agent harness, shipped as a Python SDK update in April 2026 and as the hosted Agents API in September 2026. | Open source | SDK and Agents API use standard token and tool pricing. The Agents API has no additional fee. |
MastraTypeScript agent framework. Mastra Code is the terminal agent; AgentController is the extracted loop, in @mastra/core 1.47.0 or later. | Open source | Mastra Code and AgentController are announced as open source. No license fee is stated in the posts we cited. |
OpenHandsMIT-licensed project to build and run AI coding agents: start locally, automate workflows, use any model. | MIT | The OpenHands repository is MIT-licensed. Hosted plans are not priced on this page. |
Launches and updates
OpenAI Agents API
OpenAI AgentsOpenAI's Agents API, in public beta from September 10, 2026, exposes the Codex harness and an optional hosted sandbox.
Category: Agent infra
Pricing: Usage-based
OpenAI Agents SDK sandbox harness
OpenAI AgentsOn April 15, 2026, OpenAI's Agents SDK gained a sandbox-aware harness for files, commands, and long-running tasks. Python shipped first.
Category: Frameworks
Pricing: Open source
Questions
What is the OpenAI Agents API?
Announced September 10, 2026, the Agents API is a public beta that exposes the harness behind Codex. OpenAI maintains the harness. There is no additional fee beyond tokens and tools. An optional hosted sandbox uses Codex's sandbox infrastructure.
What is the Agents SDK?
The April 15, 2026 SDK update adds sandbox-aware orchestration, filesystem tools, configurable memory, and a Manifest for mounting files from local disk or cloud storage. It launched in Python first.
What are alternatives to OpenAI Agents?
Mastra's AgentController is an open-source class in @mastra/core. OpenHands is a MIT-licensed workspace for running agents.