Top 7 Open-Source Vector Databases: Faiss vs. Chroma & More
As AI Agents and models increasingly rely on high-dimensional data retrieval, selecting an open-source vector database becomes critical for enterprise deployment.
We’ve identified the top 7 open-source vector databases and compared them in terms of scalability, performance, and real-world AI deployment:
Selection criteria
To ensure a focused selection process while aligning with key vector database use cases, we applied the following publicly verifiable criteria:
- Over 10k GitHub stars
- Over 100 contributors
Note: All vector databases should indicate their license
Top 7 open-source vector databases analyzed
Redis (Redis-Search and Redis-VSS)
Redis’s broad adoption and in-memory architecture make it well-suited for fast, large-scale vector searches, including hybrid queries that combine vectors with filters.
It is designed to return results immediately at high volumes, which makes it an appropriate choice for high-throughput AI applications such as real-time recommendation systems or chatbots that require low-latency similarity lookups.
Key features include:
- In-memory vector search: Optimized for high-speed lookup of embeddings.
- Hybrid queries: Combines key-value lookups with vector search.
Performance/unique points:
- Ideal for recommendation systems and low-latency AI applications.
Figure 1: Redis VB Diagram.1
Facebook AI Similarity Search (Faiss)
Faiss (by Facebook/Meta) is a library optimized for performance. It can handle billions of vectors and leverage GPUs for search, allowing for fast query speeds.
It’s widely used in academia and industry for embedding indexing and nearest-neighbor search at scale. Faiss is optimal for projects that need a highly efficient engine embedded into ML/AI pipelines (e.g., large-scale image or text similarity searches)
Note: Faiss is not a standalone DB and lacks features such as persistence or clustering. It is most suitable for workloads that prioritize raw processing speed and where external systems can handle data storage and management.
Key features include:
- Versatile similarity search: Supports multiple methods for high-dimensional similarity search (L2 Euclidean, inner product, and cosine for normalized vectors).
- Compressed indexes: Provides binary vector and quantization techniques to compress vectors, enabling efficient storage with minimal loss of accuracy.
- Advanced index structures: Implements various indexing structures (e.g., HNSW, NSG) on top of raw vectors to speed up nearest neighbor queries on large datasets.
- GPU acceleration: Provides GPU implementations that replace CPU indexes and automatically handle memory transfers.
Performance/unique points:
- Scalability: Capable of searching through very large collections of vectors by supporting on-disk indexes, including datasets too big to fit in RAM.
- Production usage: Developed by Meta AI Research, Faiss is used in production for large-scale similarity search and clustering tasks.
- Tuning tools: Comes with evaluation and parameter-tuning tools out of the box, making it suitable for both research experimentation and production deployments.
Milvus
Milvus is an open-source platform with industrial AI applications and an active community. It is focused on production environments (e.g., large recommendation systems, video/image search, or any AI workload handling massive vector corpora) where a user needs indexing and fault tolerance.
It offers enterprise features (such as replication and backups), making it well-suited to big data use cases.
Key features include:
- APIs for unstructured data: Provides a set of APIs and SDKs to manage and query unstructured data (embeddings) easily.
- Cloud-native & portable: Provides a consistent experience across environments, e.g., on a laptop, a local cluster, or the cloud, thanks to its cloud-native architecture.
- High availability: Includes replication and failover/failback, ensuring reliability for production use cases.
Performance/unique points:
- Benchmark speed: Milvus claims millisecond-level search latencies even for trillion-vector collections.2
- Active ecosystem: A graduate project under the LF AI & Data Foundation, indicating an active community and governance structure.
Figure 2: Milvus Architecture Diagram3
Qdrant
Qdrant is an open-source vector database written in Rust, designed for high performance and real-time data updates. It is well-suited for applications that require immediate similarity search on continuously changing data, such as live recommendation systems or frequently updated AI services.
Qdrant also supports filtering and geospatial search. It can store payload metadata alongside vectors and apply conditional filters to query results, which is helpful for applications such as personalized recommendations or location-based search.
It is a strong choice when you need high-speed performance at scale, along with real-time data updates in machine-learning applications.
Key features include:
- Filtering: Supports attaching JSON metadata (“payload”) to vectors and filtering search results based on those fields (e.g., keyword matches, numeric ranges, geo-location filters).
- Hybrid vector search: Combines dense vector search with sparse vector methods, incorporating keyword scoring alongside vector-embedding similarity.
- Vector quantization: Offers built-in quantization options to compress vectors in memory, cutting RAM usage by up to 97%.
- Distributed: Supports sharding and replication for horizontal scaling, plus features like zero-downtime rolling updates.
Performance/unique points:
- Memory efficiency: The quantization feature significantly reduces RAM usage, enabling larger datasets to be served from memory.
- Integration: Provides an API (REST and gRPC) for managing and querying the vector store.
- Neural search: Suited for semantic search applications where metadata and vector similarity must be combined.
Figure 3: High-level overview of Qdrant’s Architecture.4
PostgreSQL (pgvector Extension)
The pgvector extension brings vector similarity search to PostgreSQL, enabling teams to work within the familiar Postgres ecosystem. It is beneficial when you want to avoid deploying a separate vector database, such as when adding vector capabilities to an application’s existing SQL database for a few million embeddings.
PostgreSQL provides basic vector search alongside traditional SQL querying in a single system. In practice, pgvector is most effective when:
- Data volumes are moderate.
- Integration simplicity is more important than achieving the highest possible performance offered by specialized vector databases.
Key features include:
- Extension-based vector search: Uses pgvector to enable vector similarity search within PostgreSQL.
- Indexing for speed: Supports IVF-based approximate nearest neighbor search.
- Querying: Enables hybrid queries mixing vector similarity with SQL filters.
- Common distance metrics: Supports Euclidean, inner product, and cosine distance.
Performance/unique points:
- Integration: Allows storage of vectors alongside relational data.
- Adoption: Compatible with existing PostgreSQL setups and client libraries.
- Exact vs approximate search: Provides both precise and high-performance search options.
Chroma
Chroma is an open-source embedding database designed to be lightweight and developer-friendly. It works well for use cases such as conversational AI memory, semantic document search, and early-stage recommendation systems.
Its focus on language embeddings and integration with machine learning frameworks, including tools such as LangChain and PyTorch pipelines, enables teams to set up an embedding store and run similarity queries with minimal effort.
Chroma is most suitable for quickly deploying an AI-driven search or question-answering system and gradually scaling it, rather than for supporting workloads that require billions of vectors from the outset.
Key features include:
- Embedding storage & metadata: Designed to store embedding vectors along with their metadata, allowing organization and retrieval of high-dimensional data.
- Built-in vector generation: Supports embedding documents and queries (with integration to models), enabling semantic search and retrieval-augmented generation use cases.
- Similarity search: Provides optimized search over embeddings to find relevant vectors and supports high throughput with minimal latency.
- LLM integration: AI-native design focused on Large Language Model applications – making knowledge and facts easily pluggable into LLM workflows.
Performance/unique points:
- AI-native design: Chroma’s architecture is tailored for AI applications, simplifying the development of LLM-powered apps by offering straightforward APIs and integration hooks.
- Performance: Emphasizes low-latency operations over large volumes of embeddings, as noted by its “speed” focus in design.
- Developer experience: Prioritizes developer experience with simple setup and usage, which has contributed to its adoption.
Weaviate
Weaviate is a cloud-native vector database that integrates a knowledge graph and modular machine learning models, enabling contextual semantic queries over vector data. It is well-suited for enterprise search, question answering, and other applications that need AI-driven insights over complex datasets. It works well when text or images are vectorized and connected to structured knowledge.
Weaviate offers GraphQL APIs, real-time queries, and support for multimodal data, such as text and images. This makes it effective for building semantic search or recommendation systems that need to understand relationships and meaning.
Its combination of vector search, filtering capabilities, and knowledge graph features distinguishes it from other systems. It is used in industry for applications such as genomic search, FAQ automation, and content recommendation, where contextual accuracy is as important as performance.
Key features include:
- Vector search: Claims to execute k-NN searches on millions of objects within a few milliseconds.5
- Modular architecture: Extensible via modules that integrate with ML model services (e.g., OpenAI, Cohere, HuggingFace).
- Hybrid search capabilities: Allow combining vector search with keyword filtering in the same query.
- Production-ready features: Includes clustering, replication, authentication, and security features for scalability.
Performance/unique points:
- Dual search (semantic + lexical): Supports both vector similarity and symbolic (lexical) search in one engine.
- Plug-and-play ML integration: Enables on-the-fly text vectorization or use of pre-vectorized data.
What is a vector database?
A vector database is a specialized database designed to store, index, and efficiently retrieve high-dimensional vector embeddings. Instead of traditional structured data such as tables and rows, vector databases store numerical representations of data points. Vector databases are essential for machine learning, AI, and similarity search applications.
With a vector database, you can:
- Find similar images or videos, otherwise known as reverse research (e.g., Google Lens)
- Store face embeddings and match them against a query for authentication or search (e.g., Apple Face ID)
- Identify objects in images/videos and find relevant matches
Key features of open-source vector databases
High-dimensional vector indexing
Stores and indexes vector embeddings (e.g., from text, images, or audio) for similarity search.
Similarity search support
Enables vector similarity queries using distance metrics like Euclidean, cosine, and inner product.
Scalability for large datasets
Designed to handle millions to trillions of vectors, often through distributed or sharded architectures.
Hybrid query capabilities
Combines vector search with structured filters such as keywords, metadata fields, or geo-location.
Extensible APIs and integrations
Provides REST, gRPC, or SDK support for embedding into ML workflows and vectorization pipelines.
GPU acceleration (in some tools)
Libraries such as Faiss provide GPU support to accelerate large-scale similarity searches.
Metadata storage
Supports attaching structured metadata (e.g., JSON payloads) to vectors for filtered or contextual retrieval.
Vector quantization and compression
Reduces memory usage through techniques like product quantization or binary encoding.
Cloud-native deployment options
Many tools support containerized and orchestrated environments (e.g., Docker, Kubernetes) with features like replication and failover.
Open licensing & community contributions
Released under open-source licenses (e.g., Apache 2.0, MIT) with active GitHub development and transparent issue tracking.
What are vector search extensions?
Vector search extensions add vector search capabilities to existing databases, such as relational (SQL) or key-value stores, without requiring a dedicated vector database. These extensions allow users to perform similarity searches alongside traditional queries within the same database environment.
Key features of vector search extensions:
- Embedded in existing databases: No need to introduce a separate vector database.
- Supports structured and vector queries: Enables combining vector-based similarity search with structured filters, SQL joins, and metadata-based lookups.
- Leverages existing indexing techniques: Uses approximate nearest neighbor (ANN) indexing within relational database storage.
- Best for hybrid applications: Ideal for adding AI-powered search to existing enterprise databases.
FAQ: Open-source vector databases
Reference Links
Cem's work has been cited by leading global publications including Business Insider, Forbes, Washington Post, global firms like Deloitte, HPE and NGOs like World Economic Forum and supranational organizations like European Commission. You can see more reputable companies and resources that referenced AIMultiple.
Throughout his career, Cem served as a tech consultant, tech buyer and tech entrepreneur. He advised enterprises on their technology decisions at McKinsey & Company and Altman Solon for more than a decade. He also published a McKinsey report on digitalization.
He led technology strategy and procurement of a telco while reporting to the CEO. He has also led commercial growth of deep tech company Hypatos that reached a 7 digit annual recurring revenue and a 9 digit valuation from 0 within 2 years. Cem's work in Hypatos was covered by leading technology publications like TechCrunch and Business Insider.
Cem regularly speaks at international technology conferences. He graduated from Bogazici University as a computer engineer and holds an MBA from Columbia Business School.
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