This guide to data annotation tools for Generative AI explains how teams can improve model accuracy and align LLMs with human values by using the right platforms and workflows. The use of Generative AI has increased significantly, but many projects fail due to incomplete, biased, or poorly labeled data. To address this, teams need structured feedback loops like Reinforcement Learning from Human Feedback (RLHF) and specialized data-annotation platforms that can manage multimodal data, annotation at scale, and automated quality checks. The six must-have features of a modern annotation platform include RLHF support, multimodal editors, AI-assisted labeling and active learning, collaboration and quality control, secure infrastructure, and SDK/API and cloud integrations. The best data annotation tools for Generative AI are those that can streamline workflows, improve scalability, and ensure model performance in diverse AI applications. Encord stands out as a leading platform that supports multimodal data annotation within a single platform, integrates RLHF workflows, and provides secure AI-assisted workflows. Other notable platforms include Scale AI, Labelbox, Kili, Appen, Dataloop, and SageMaker.