BoltDB is an embedded key/value database written in Go. It supports fully serializable transactions, ACID semantics, and lock-free MVCC with multiple readers and a single writer. BoltDB uses a single-level, zero-copy, B+tree data storage, which allows fast read access and does not require recovery in the event of a system crash.


In 2011, Howard Chu introduced MDB, a memory-mapped database backend for OpenLDAP, later renamed to [LMDB] ( Memory-Mapped Database). In 2013, BoltDB was initially started by Ben Johnson as a port of LMDB to Go, but then the two projects diverged as the author of Bolt decided to focus on simplicity and providing the easy-to-use Go API. The goal of BoltDB became to provide a simple, fast, and reliable database for projects that don't require a full database server such as Postgres or MySQL. With BoltDB being stable, its API fixed, and its file format fixed, the author considered the project a success. Leaving it in such a state, the project was abandoned by its author in 2017.

Query Interface

Custom API


Virtual Views

Bolt allows only one read-write transaction at a time but allows as many read-only transactions as you want at a time. Each transaction has a consistent view of the data as it existed when the transaction started. BoltDB recommends three types of transactions: read-write transactions with `DB.Update`, read-only transactions with `DB.View` and batch read-write transactions with `DB.Batch`. Along with the three recommended transactions, BoltDB also allows manual transaction management with `DB.Begin`.

Concurrency Control

Multi-version Concurrency Control (MVCC)

BoltDB allows only one read-write transaction at a time.


Not Supported

Bolt saves data into a single memory-mapped file on disk. It doesn’t have a separate journal or write-ahead log.

Storage Model


BoltDB uses key/value storage, which does not involve rows or columns.

Isolation Levels





Not Supported

Foreign Keys

Not Supported

Data Model


Bolt is a key-value store that provides an ordered map, which allows easy access and lookup.

System Architecture


Query Compilation

Not Supported

Storage Organization

Copy-on-Write / Shadow Paging

BoltDB saves data into a single memory-mapped file on disk. Write-ahead log is not necessary since BoltDB only deals with one file at a time. With copy-on-write, when writing to a page, BoltDB makes updates on the copy of the original page and updates the pointer to point at the new page upon commit.

BoltDB Logo

Source Code

Tech Docs


Ben Johnson

Country of Origin


Start Year


End Year


Project Type

Open Source

Written in


Supported languages


Inspired By


Operating Systems

Android, BSD, iOS, Linux, OS X, Solaris, Windows