Vector Databases & RAG Infrafree

pgvector

Open-source vector similarity search extension for Postgres

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What pgvector does

  • Open-source vector similarity search extension for Postgres
  • HNSW and IVFFlat indexes with exact and approximate search
  • Available on most managed Postgres hosts

pgvector — straight answers

What is pgvector?

pgvector is listed under Vector Databases & RAG Infra, in the Code & Development category on Flocci AI Tools. Open-source vector similarity search extension for Postgres. It is free, with no paid plan attached, and it lives at github.com.

Is pgvector free?

pgvector is listed as fully free — there is no paid tier attached to it in the catalog. That makes it one of the 397 entries on Flocci AI Tools with no upgrade path built in.

Can I use pgvector in a browser, or is there an app?

pgvector needs to be installed or self-hosted — it doesn't run in a browser tab. It is available on self-hosting.

What can pgvector do?

pgvector does 3 things the catalog singles out: Open-source vector similarity search extension for postgres; hnsw and ivfflat indexes with exact and approximate search; available on most managed postgres hosts.

What is the best free alternative to pgvector?

Vespa is the closest free alternative: it sits in the same Vector Databases & RAG Infra sub-category and is free. LanceDB, Microsoft GraphRAG and Milvus also start free. The full list is on the alternatives page.

See the full list →

pgvector alternatives

Compare all alternatives →

Qdrant

Vector Databases & RAG Infra
freemium
  • Open-source Rust-based vector database, self-hostable for free with no scale limit
  • Managed free tier cluster (0.5 vCPU/1GB RAM/4GB disk) for prototyping RAG apps with no card required for OSS use
  • Hybrid Cloud option to run managed clusters on your own infrastructure for compliance-sensitive RAG
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Weaviate

Vector Databases & RAG Infra
freemium
  • Free managed cloud plan (100k objects, 1GB memory, 10GB disk) to explore without self-hosting
  • Open-source core project can be self-hosted for free indefinitely, same engine as the managed cloud
  • Built-in hybrid (vector + keyword) search and native embedding/query-agent integrations
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Chroma

Vector Databases & RAG Infra
freemium
  • Fully open-source embedded/self-hosted vector store, the default choice bundled into countless RAG tutorials and frameworks
  • Chroma Cloud managed tier starts with free usage credits, no subscription
  • Simple Python/JS-native API designed to be the easiest on-ramp to RAG for developers
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Microsoft GraphRAG

Vector Databases & RAG Infra
free
  • Builds knowledge graphs and community summaries from private text for RAG
  • Answers global, dataset-wide questions that vector RAG misses
  • Open-source Python library and CLI
  • Works with OpenAI-compatible and local models
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Milvus

Vector Databases & RAG Infra
free
  • Cloud-native Apache-2.0 vector database for large-scale similarity search
  • Runs from a single-file Lite mode to distributed clusters
  • Managed Zilliz Cloud has a separate free tier
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LanceDB

Vector Databases & RAG Infra
free
  • Embedded, developer-friendly retrieval library for multimodal AI
  • Columnar Lance format with vector and full-text search
  • Apache-2.0
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Head-to-head comparisons

pgvector vs Qdrantpgvector vs Weaviatepgvector vs Chromapgvector vs Microsoft GraphRAGpgvector vs Milvuspgvector vs LanceDB