Haystack is an open-source NLP framework developed by Deepset, designed for creating sophisticated search platforms and conversational Artificial Intelligence applications. It enables developers to build powerful, end-to-end search pipelines that can handle large-scale, complex queries with high accuracy. Haystack leverages state-of-the-art transformer models, supports various backends, and is highly customizable, making it ideal for enterprise-level search and Q&A platforms. It also includes features for document retrieval, question answering, and semantic search.