Haystack is an open-source NLP framework developed by Deepset, designed to facilitate the creation of advanced search systems and conversational AI applications. It enables developers to build powerful, end-to-end search pipelines capable of handling large-scale, complex queries with high accuracy. Haystack leverages state-of-the-art transformer models and supports various backends, offering a high degree of customization that makes it ideal for enterprise-level search and Q&A systems.