Epsilla
maintenanceby Epsilla Inc. · since 2023 · also known as EpsillaDB
C++ vector database using parallel graph traversal; vendor now focuses on an agent platform.
maintenance. No tagged release since v0.3.16 (March 2025); Epsilla Inc. now sells an AI agent platform rather than the vector database.
Overview
Epsilla is an open-source vector database written in C++ that claims large speedups over standard HNSW by traversing its graph index in parallel, with support for metadata filtering, hybrid dense/sparse retrieval and a REST API, plus an embedded Python mode. Epsilla Inc. (YC-backed) has since shifted its business to an agent-as-a-service platform and no longer markets the database as a product. The repository still sees occasional commits, but there has been no tagged release since v0.3.16 in March 2025. Treat it as low-activity; choose Qdrant, Milvus or pgvector for new work.
Strengths & trade-offs
Strengths
- +Parallel graph traversal for fast ANN on multi-core machines
- +Embedded Python mode for local use
- +Simple REST API
Trade-offs
- −Vendor focus has moved away from the database
- −No release since early 2025
- −Small community and few integrations
- −No clustering
Great for
- +Experimenting with parallel graph ANN
- +Small self-hosted RAG prototypes
Think twice for
- −Production systems needing long-term support
- −Large or distributed deployments
Capabilities
Native or official first-party support · 2 of 25 tracked
Scale & consistency
- Comfortable data size
- Small · ≤ 100 GB
- Horizontal scaling
- None
- Multi-region
- No
- Transactions
- None
- Consistency
- Eventual
- Schema
- Strict
- Architecture
- Single node, Embedded, Client server
- Query languages
- Epsilla API (JSON)
Deployment
Ecosystem
Alternatives to Epsilla
Rust vector search engine with rich payload filtering, quantization and a managed cloud.
epsilla vs qdrant →Cloud-native, distributed open-source vector database built for billions of vectors.
epsilla vs milvus →Open-source retrieval database for AI apps, from embedded Python to serverless Chroma Cloud.
epsilla vs chroma →Open-source AI-native vector database with hybrid search, modules for embeddings and multi-tenancy.
epsilla vs weaviate →The standard Postgres extension for vector similarity search with HNSW and IVFFlat indexes.
epsilla vs pgvector →Google Cloud's managed ANN service built on ScaNN, now part of Gemini Enterprise Agent Platform.
epsilla vs vertex-ai-vector-search →Epsilla FAQ
What is Epsilla?
Epsilla is a vector database by Epsilla Inc., first released in 2023. Epsilla is an open-source vector database written in C++ that claims large speedups over standard HNSW by traversing its graph index in parallel, with support for metadata filtering, hybrid dense/sparse retrieval and a REST API, plus an embedded Python mode. Epsilla Inc. (YC-backed) has since shifted its business to an agent-as-a-service platform and no longer markets the database as a product. The repository still sees occasional commits, but there has been no tagged release since v0.3.16 in March 2025. Treat it as low-activity; choose Qdrant, Milvus or pgvector for new work.
Is Epsilla open source?
Yes. Epsilla is open source. License: Apache License 2.0.
Does Epsilla support ACID transactions?
No. Epsilla does not provide ACID transactions; its consistency model is eventual.
Does Epsilla scale horizontally?
Epsilla does not scale horizontally; it runs on a single node, so you scale it up rather than out. It is comfortable at small scale (≤ 100 GB).
How can I run Epsilla?
You can self-host it and embed it in your application.
What is Epsilla best for?
Epsilla is a strong fit for experimenting with parallel graph ANN and small self-hosted RAG prototypes. Think twice for production systems needing long-term support.
What are the best alternatives to Epsilla?
Common alternatives to Epsilla include Qdrant, Milvus, Chroma, Weaviate and pgvector. The right choice depends on your workload, scale and hosting; WhichDB's smart match ranks them against your requirements.
Is Epsilla still maintained?
Epsilla is in maintenance mode. No tagged release since v0.3.16 (March 2025); Epsilla Inc. now sells an AI agent platform rather than the vector database.
How popular is Epsilla?
Epsilla ranks #339 of 844 databases on the WhichDB Score (7.6/100), and #21 among vector databases. The score combines public adoption signals such as package downloads, GitHub activity, job posts and developer discussion.