Open Glean

Open Glean is a graph database built on object storage designed to manage memory, context, and relationships for AI agents.

HydraDB is an object-store-native distributed graph database built in Rust to serve as a memory and context layer for AI systems. It connects structured data, entity relationships, and temporal versioning to help AI agents understand how information links and changes over time. Unlike vector databases that rely on semantic similarity, HydraDB enables agents to traverse explicit connections between entities, events, and user preferences across sessions. It supports OpenCypher, GraphBLAS-accelerated traversal, and Neo4j-compatible Bolt protocols. The architecture uses tiered storage—hot in-memory, warm NVMe SSD, and cold object storage—to scale automatically.

Open Glean at a glance

Best for: Founder, Software engineer
Runs on: API, self-hosted, open source
Pricing: Free plan; Ship plan (usage-based, $6/1M overage, $0.50/GB-month); Scale plan ($0.25/GB-month); Enterprise (contact sales)
Released: September 2026
Category: AI search engine
Website: hydradb.com

Key features

Temporal versioning for historical state tracking
Neo4j-compatible Bolt and HTTP API support
GraphBLAS-accelerated traversals
Multi-tenant isolation and auto-scaling
Integration with over 100 data sources
Tiered storage system using S3, NVMe, and memory

Use it for

Building agent memory systems
Developing company brains and ontologies
Enabling agentic actions based on context
Managing structured state and context graphs

Alternatives to Open Glean

HelixDB — Combines graph, vector, and full-text search in one engine.
OpenViking — Unifies agent memory, knowledge RAG, and skills into a single directory structure.
Cognee — Persistent memory for AI agents using graph, vector, and relational retrieval.
Alook — Connects existing local coding agents to team communication channels.
seekdb — Unifies relational, vector, and text data for production-grade AI agents.
Graphiti — Provides incremental updates and hybrid retrieval for knowledge graphs.
Beads — Prevents context loss with version-controlled, dependency-aware storage.
claude-mem — It shares persistent, searchable agent memory across sessions and devices.
Mnemosyne — It provides sub-millisecond memory access with no external service costs.
MemPalace — Achieves high recall with local-first storage and zero API calls.
Tigerless Agent Memory — Maintains agent history in portable, greppable Markdown files without API keys.
M-Flow — It achieves a 93.7 percent top-one hit rate using a conical memory architecture.

All Open Glean alternatives