Redis vs MongoDB
Redis is an in-memory data store optimized for sub-millisecond latency with vector search, caching, and real-time analytics. MongoDB is a document database built for flexible schemas, rich queries, and horizontal scaling with Atlas Vector Search for AI workloads. Redis for speed-critical caching and real-time data; MongoDB for complex document storage and queries.
Redis Vector
Sub-millisecond vector search in memory
CRedis Source Available Licensetraditional
Key Features
- Sub-millisecond latency
- In-memory vector index
- HNSW & FLAT algorithms
- Hybrid vector + tag filtering
- Redis Stack modules
- Redis Enterprise Cloud
Pricing
Open SourceFree
Cloud (Free)$0
Cloud (Essentials)From $5/mo
EnterpriseCustom
Use Cases
Real-time recommendationsChatbot session memoryLow-latency semantic searchCaching + similarity
MongoDB Atlas Vector Search
Vector search built into the #1 document database
C++SSPL (server) / Proprietary (Atlas)traditional
Key Features
- Native MongoDB integration
- Aggregation pipeline queries
- Pre-filtering with MQL
- Atlas Search (full-text + vector)
- Global multi-cloud deployment
- SOC 2 & HIPAA compliant
Pricing
Free (Shared)$0
DedicatedFrom ~$57/mo
EnterpriseCustom
Use Cases
Semantic search in existing appsE-commerce recommendationsContent discoveryFraud detection
Verdict
Redis for caching, real-time workloads, and vector search with minimal latency. MongoDB for document-heavy applications with complex queries and Atlas Vector Search.
Choose Redis Vector if you need:
- ✓Sub-millisecond latency
- ✓In-memory vector index
- ✓HNSW & FLAT algorithms
Choose MongoDB Atlas Vector Search if you need:
- ✓Native MongoDB integration
- ✓Aggregation pipeline queries
- ✓Pre-filtering with MQL