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FoundationDB vs SlateDB

FoundationDB: Apple's ordered, strictly serializable distributed key-value store, built to have layers on top. SlateDB: Embedded LSM storage engine that writes straight to object storage like S3.

key differences

  • Horizontal scaling is native in FoundationDB and none in SlateDB.
  • Only FoundationDB has pub/sub, encryption at rest.
  • Only SlateDB has ttl / expiry, compression, time travel.
  • SlateDB can run embedded in your application process.

choose foundationdb for

  • +Metadata stores for larger systems (catalogs, object stores)
  • +Foundation for custom databases and layers
  • +Multi-tenant app backends via the Record Layer
  • +Transactional queues and job systems

best at · OLTP, Metadata, Queue

choose slatedb for

  • +State backends for stream processors and serverless compute
  • +Metadata stores for object-storage-native systems
  • +Durable logs and queues on S3
  • +Embedding a KV engine in diskless containers

best at · Embedded, Streaming, Metadata

FoundationDBApple's ordered, strictly serializable distributed key-value store, built to have layers on top.
SlateDBEmbedded LSM storage engine that writes straight to object storage like S3.
overview
Primary model
Key-Value
Key-Value
Also supports
–
–
Type
Database engine
Embedded library
Status
Active
Active
Developer
Apple
SlateDB contributors (Commonhaus Foundation)
First release
2013
2024
Latest version
7.3.77 (Apr 16, 2026)
0.17.0 (Sep 29, 2026)
License
Open source (permissive)Apache License 2.0
Open source (permissive)Apache License 2.0
Free tier
✓
✓
popularity
WhichDB Score
36.8
19.7
Rank
#54
#163
GitHub stars
16.8K
3.6K
Stack Overflow questions
37
–
scale & guarantees
Comfortable data size
Large (≤ 1 PB)
Large (≤ 1 PB)
Horizontal scaling
Native
None
Multi-region
Read replicas
None
ACID
Full
Full
Consistency
Strong
Strong
Schema
Schemaless
Schemaless
Architecture
Distributed, Client server
Embedded, Shared storage
deployment
Self-hosted
✓
✓
Vendor-managed cloud
—
—
Serverless
—
—
Embedded
—
✓
Edge
—
—
Clouds
–
–
capabilities
Transactions
✓
✓
Joins
—
—
Secondary indexes
—
—
Full-text search
—
—
Vector search
—
—
Geospatial
—
—
JSON
—
—
Change data capture
—
—
Triggers
—
—
Stored procedures
—
—
Materialized views
—
—
TTL / expiry
—
✓
Pub/Sub
✓
—
Columnar storage
—
—
In-memory
—
—
Durable persistence
✓
✓
Compression
—
✓
Encryption at rest
✓
—
Role-based access
—
—
Time travel
—
✓
Branching
—
—
Online schema changes
—
—
Streaming ingest
—
—
Offline sync
—
—
Runs in WebAssembly
—
—
interfaces
Query languages
FoundationDB API
Rust API
Client languages
C, Python, Java, Go, Ruby, Rust, JavaScript, Swift
Rust, Go, Java, JavaScript, Python
Best for
OLTP, Metadata, Queue
Embedded, Streaming, Metadata
Add more to this comparisonNot sure either fits? Try smart match

FoundationDB vs SlateDB: FAQ

What is the difference between FoundationDB and SlateDB?

FoundationDB: Apple's ordered, strictly serializable distributed key-value store, built to have layers on top. SlateDB: Embedded LSM storage engine that writes straight to object storage like S3. Horizontal scaling is native in FoundationDB and none in SlateDB. Only FoundationDB has pub/sub, encryption at rest. Only SlateDB has ttl / expiry, compression, time travel.

When should I choose FoundationDB over SlateDB?

Choose FoundationDB for metadata stores for larger systems (catalogs, object stores); foundation for custom databases and layers; and multi-tenant app backends via the Record Layer. Choose SlateDB for state backends for stream processors and serverless compute; metadata stores for object-storage-native systems; and durable logs and queues on S3.

Is FoundationDB or SlateDB more popular?

FoundationDB ranks #54 on the WhichDB Score (36.8/100) and SlateDB ranks #163 (19.7/100). Popularity is not fit: check the requirements that matter for your project.

Are FoundationDB and SlateDB open source?

Yes. FoundationDB is open source. License: Apache License 2.0. Yes. SlateDB is open source. License: Apache License 2.0.