HumanLayer is an API and SDK that enables AI agents to interact with humans for feedback, approvals, and guidance. By integrating HumanLayer, developers can ensure critical AI decisions are overseen by humans, create custom approval workflows, manage transitions between software- and human-driven processes, and collect valuable human feedback to improve AI systems. It supports integration with popular frameworks and LLMs, making it a versatile tool for various applications requiring human oversight on AI outputs.