Neo4j
What it is: Leading graph database. Native graph storage and processing. Relationships are first-class citizens, not foreign keys.
What It Does Best
Relationship queries. "Friends of friends," network analysis, recommendation engines. What's painful in SQL is natural in Cypher.
Pattern matching. Find complex patterns across connected data. Fraud detection, knowledge graphs, social networks.
Real-time traversals. Multi-hop queries stay fast. No join explosions at query time.
Key Features
Cypher query language: Intuitive pattern-matching syntax for graph queries
Native graph storage: Optimized for traversing relationships
ACID transactions: Full transactional support for data integrity
Graph algorithms: Built-in algorithms for pathfinding, centrality, community detection
Visualization: Built-in graph visualization tools
Pricing
Community Edition: Free, GPL license (single instance only)
Enterprise: Contact for pricing (clustering, backup, monitoring)
Aura Free: Free forever with limits (200k nodes, 400k relationships)
Aura Pro: From $65/month, usage-based scaling
When to Use It
✅ Social networks and connections
✅ Recommendation engines
✅ Fraud detection and network analysis
✅ Knowledge graphs and master data
✅ Dependency tracking and impact analysis
When NOT to Use It
❌ Simple tabular data (use relational DB)
❌ Aggregate analytics on large datasets (use data warehouse)
❌ Unconnected data with few relationships
❌ High-volume transactions (not optimized for OLTP at scale)
❌ Simple CRUD operations without relationships
Common Use Cases
Social networks: Friends, followers, connections, influence
Recommendations: "People who bought X also bought Y" queries
Fraud detection: Identify suspicious patterns in transaction networks
Knowledge graphs: Connect and query related information
Network management: IT infrastructure dependencies and impact
Neo4j vs Alternatives
vs SQL databases: Neo4j 1000x faster for relationship queries, SQL better for tabular data
vs Amazon Neptune: Neo4j more mature, Neptune fully managed AWS service
vs ArangoDB: ArangoDB multi-model, Neo4j pure graph specialist
Unique Strengths
Cypher language: Most intuitive graph query language
Native graph engine: Purpose-built for relationship traversals
Ecosystem maturity: Most established graph database
Visualization: Built-in tools for exploring graph data visually
Bottom line: If your data is about connections and relationships, stop fighting SQL joins. Neo4j makes complex relationship queries simple and fast. Cypher is intuitive once you think in graphs.