Best CAST AI Alternatives

Vespa is an open-source serving engine with 6K+ GitHub stars for hybrid search combining vector similarity, BM25 text ranking, and structured filtering in a single query. Built by Yahoo for web-scale, it handles billions of documents with millisecond latency. Features real-time indexing, ML model serving, tensor computation, and ACID-compliant writes. Supports custom ranking models, query federation, and geographic search. Used for recommendation systems, personalization, and RAG.

OpenCost is a CNCF-certified open-source tool for real-time Kubernetes cost monitoring that maps cloud spend directly to namespaces, deployments, pods, and labels. It provides granular cost allocation across teams and projects without vendor lock-in, supporting AWS, GCP, Azure, and on-premises clusters as the industry standard for open-source FinOps visibility in cloud-native environments.

RAGFlow is an open-source RAG engine with 76K+ GitHub stars that provides deep document understanding for building knowledge-based AI applications. Optimizes chunking for 20+ document types including PDFs, Word docs, presentations, and images using layout-aware parsing. Features template-based chunking strategies, citation with source references, multi-recall retrieval combining keyword and semantic search, and a visual knowledge base management interface with drag-and-drop document upload.