Vespa : Real-time vector search and ranking engine

Vespa is an open-source platform for real-time vector search, text search, and machine-learned ranking, developed by Yahoo (now Oath/Verizon Media). It combines large-scale serving capabilities with the flexibility of a full-featured search engine, making it suitable for use cases such as recommendation systems, semantic search, personalized feeds, and large-scale retrieval-augmented generation (RAG) pipelines.

Unlike many vector-only databases, Vespa supports hybrid search (combining vector similarity with structured filtering, text relevance, and ML models), enabling complex query logic and custom ranking. It’s optimized for low-latency inference at scale and supports indexing, filtering, and ranking billions of documents in production environments.

Key benefits include:

• Unified support for dense vector search, keyword search, and ML ranking
• Real-time updates, filtering, and aggregation at query time
• Production-ready for large-scale, low-latency applications

What are the main features of Vespa?

Hybrid search engine for vectors, text, and structure

Vespa is designed for flexible, large-scale search across different data modalities.

• Combine dense vector similarity with keyword relevance and structured filters
• Query language supports complex logical conditions, scoring functions, and boosting
• Useful for semantic search, e-commerce, question answering, and personalization

Built-in machine-learned ranking (MLR)

Vespa natively supports ranking using machine learning models, directly during search.

• Deploy linear, tree-based, or ONNX models for scoring
• Apply inference at query time across thousands of candidate results
• Rerank results using custom relevance logic or neural models

Real-time indexing and updates

Vespa provides real-time ingestion and updates without downtime.

• Documents and vectors can be updated individually or in bulk
• Low-latency write path suitable for dynamic content (e.g., news, user behavior)
• Indexes support high availability and consistency

Scalable and distributed architecture

Vespa is built for large-scale deployments, running across multiple nodes with full fault tolerance.

• Horizontally scalable indexing, search, and ranking
• Sharding, replication, and automatic failover included
• Supports billions of documents and large embedding models in production

Advanced filtering and aggregation

Vespa supports complex filtering, grouping, and aggregation during queries.

• Use structured metadata (e.g., user attributes, product categories) in combination with vector similarity
• Compute aggregates, histograms, and top-k results efficiently
• Ideal for personalized ranking and analytics use cases

Why choose Vespa?

• All-in-one retrieval platform: Combine vector, text, and ML-powered search in one system
• Designed for production at scale: Proven in environments with billions of documents and high query volume
• Real-time performance: Ingest, update, and serve with low latency
• Fully open source: No commercial license or usage limits
• Highly configurable: Supports custom query logic, scoring models, and deployment topologies