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PoloDB vs UnQLite

PoloDB: Embedded BSON document database for Rust with a MongoDB-like API and optional wire-protocol server. UnQLite: Embedded, transactional key-value and JSON document engine in a single C file, with Jx9 scripting.

key differences

  • PoloDB is primarily a document database; UnQLite is key-value.
  • Only PoloDB has secondary indexes, compression.
  • Only UnQLite has in-memory.

choose polodb for

  • +Rust desktop and CLI apps needing local document storage
  • +Edge services wanting MongoDB-like semantics without a server
  • +Tests that stub MongoDB with an embedded store

best at · Embedded, Edge, Coordination

choose unqlite for

  • +Embedded devices and firmware needing local storage
  • +Desktop or game apps storing JSON state
  • +Local caches inside native services

best at · Embedded, IoT, Coordination

PoloDBEmbedded BSON document database for Rust with a MongoDB-like API and optional wire-protocol server.
UnQLiteEmbedded, transactional key-value and JSON document engine in a single C file, with Jx9 scripting.
overview
Primary model
Document
Key-Value
Also supports
–
Document
Type
Embedded library
Embedded library
Status
Active
Active
Developer
PoloDB project (Vincent Chan)
Symisc Systems
First release
2020
2013
Latest version
5.3.0 (Jul 26, 2026)
1.2.1 (May 1, 2026)
License
Open source (permissive)Apache License 2.0
Open source (permissive)BSD 2-Clause
Free tier
✓
✓
popularity
WhichDB Score
3.2
4.1
Rank
#443
#419
GitHub stars
1.2K
2.3K
Stack Overflow questions
–
–
scale & guarantees
Comfortable data size
Small (≤ 100 GB)
Small (≤ 100 GB)
Horizontal scaling
None
None
Multi-region
None
None
ACID
Full
Full
Consistency
Strong
Strong
Schema
Schemaless
Schemaless
Architecture
Embedded, Client server
Embedded, In memory
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
MongoDB-like query API (subset)
Jx9, Key-value C API
Client languages
Rust, Python
C, C++, Python
Best for
Embedded, Edge, Coordination
Embedded, IoT, Coordination, Edge
Add more to this comparisonNot sure either fits? Try smart match

PoloDB vs UnQLite: FAQ

What is the difference between PoloDB and UnQLite?

PoloDB: Embedded BSON document database for Rust with a MongoDB-like API and optional wire-protocol server. UnQLite: Embedded, transactional key-value and JSON document engine in a single C file, with Jx9 scripting. PoloDB is primarily a document database; UnQLite is key-value. Only PoloDB has secondary indexes, compression. Only UnQLite has in-memory.

When should I choose PoloDB over UnQLite?

Choose PoloDB for rust desktop and CLI apps needing local document storage; edge services wanting MongoDB-like semantics without a server; and tests that stub MongoDB with an embedded store. Choose UnQLite for embedded devices and firmware needing local storage; desktop or game apps storing JSON state; and local caches inside native services.

Is PoloDB or UnQLite more popular?

UnQLite ranks #419 on the WhichDB Score (4.1/100) and PoloDB ranks #443 (3.2/100). Popularity is not fit: check the requirements that matter for your project.

Are PoloDB and UnQLite open source?

Yes. PoloDB is open source. License: Apache License 2.0. Yes. UnQLite is open source. License: BSD 2-Clause.