LMDB
LMDB: A focused embedded database for fast, durable key-value storage inside applications. Ranked #21 of 30 in Embedded Databases by our editors (6.7/10); pricing: Free plan; best for high-performance memory-mapped key-value storage.
At a glance
- Editor score6.7 / 10
- PricingFree plan
- Best forHigh-performance memory-mapped key-value storage
- Free planYes
- Paid fromFree
- Data synchronizationNo
- Facts checked20 Sep 2026
Where it wins
- Persistent memory-mapped storage with ACID transactions and MVCC
- Concurrent readers and writers with ordered range lookups
- Zero-copy access, cursors, and multiple sub-databases per environment
Where it doesn't
- No built-in synchronization support
- Runs inside applications rather than as a standalone database server
- Key-value and NoSQL access do not provide relational query features
Our verdict on LMDB
LMDB is an open-source embedded key-value database library developed by Symas for the OpenLDAP Project. It is intended for developers who need persistent storage inside an application rather than a separate database server. The library supports Windows, Linux, macOS, and other POSIX-compatible systems. Applications can access it through the C API or language bindings, with concurrent access available to threads and processes on the same host.
Its main strength is the combination of memory-mapped storage, ACID transactions, and MVCC concurrency. Readers and writers can operate concurrently, while ordered keys support range lookups and predictable traversal. Zero-copy lookup and iteration can reduce data movement between the database and application code. Cursor-based retrieval, insertion, deletion, and iteration provide a direct way to work through records, and multiple sub-databases can be kept within one environment. Optional page-level checksums and encryption support add protection options for stored data.
LMDB is a strong fit for applications that need local, durable key-value storage with a narrow NoSQL interface and direct control over the embedded database layer. It is available as open-source software with a free plan, while Symas offers separately priced support services. The platform is less suitable when an application needs built-in synchronization, a standalone database service, or relational query capabilities. Its database size is configured through the memory-map size, so deployment requires deliberate capacity planning. Choose LMDB for high-performance local storage, ordered access, and concurrent same-host workloads; choose an alternative when distributed synchronization or server-oriented operation is central to the project.
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LMDB pricing
LMDB fact sheet
| Free plan | Yes |
|---|---|
| Paid from | Free |
| Supported platforms | Windows and POSIX-compatible systems, including Linux and macOS |
| Database model | Key-value |
| Query interface | Nosql |
| Encryption | Yes |
| Data synchronization | No |
| Maximum database size | Not verified |
| Deployment | Self-hosted |
| Platforms | Windows, Linux, macOS |
| Support | Community, Docs |
| Built for | Solo, Small business, Mid-market, Enterprise (editorial estimate) |
| Pricing | Free plan |
| Website | symas.com |
| Facts checked | 20 Sep 2026 |
Alternatives to LMDB
- SQLiteA capable, zero-configuration SQL engine for applications that need local embedded storage.9.4
- H2 Database EngineA flexible embedded SQL engine for Java applications, with self-hosted server options.9.1
- FirebirdA self-hosted SQL database with replication, backups, and multiple deployment architectures.9.0
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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
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