ObjectBox C / C++ Database

This is the ObjectBox documentation for our C and C++ APIs. We strive to provide you with the easiest and fastest solution to store and retrieve data.

Jobs: We're looking for a C++ Developer with a ❤️ for performant code

Are you ready use ObjectBox? These two pages will get you up to speed:

InstallationHow to get started

Alternatively, you can also dive into some examples on GitHub right away.

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Latest Versions (Changelogs)

4.3.0 (2025-05-12)

• Windows: msvc runtime is now embedded to avoid incompatible msvcp140.dll (e.g. those shipped with some JDKs)

• External property types (via MongoDB connector): JsonToNative to support sub (embedded/nested) documents/arrays in MongoDB

• External property types (via MongoDB connector): support ID mapping to UUIDs (v4 and v7)

• Admin: add class and dependency diagrams to the schema page (view and download)

• Admin: improved data view for large vectors by displaying only the first elements and the full vector in a dialog

• Admin: detects images stored as bytes and shows them as such (PNG, GIF, JPEG, SVG, WEBP)

Sync

• Add "Log Events" for important server events, which can be viewed on new Admin page

• Detect and ignore changes for objects that were put but were unchanged

• The limit for message size was raised to 32 MB

• Transactions above the message size limit will already fail on the client now (to better enforce the limit)

• C++: add missing APIs for JWT token credentials

4.2.0 (2025-03-04)

• Extended the model by external names and types: allows defining a different name for an external database, which ObjectBox syncs with.

This prepares upcoming features for our MongoDB Sync Connector.

4.1.0 (2025-01-28)

• New query conditions for map properties (via flex properties): now supports key/value pairs for inequality conditions (e.g. greater than, less than) for string, integer and floating point values

• Vector search: add "Geo" distance type for longitude/latitude pairs

• Various internal improvements

Sync

• Add JWT authentication

• Sync clients can now send multiple credentials for login

4.0 (2024-11-11)

Note: 4.0.3 the first 4.0.x version working with ObjectBox Generator 4.0 and thus is the first full 4.0 release. For individual changes in the runtime library check the GitHub release notes: 4.0.0, 4.0.1 and 4.0.2.

• CMake stubs to easily integrate with ObjectBox Generator 4.0

• ObjectBox now supports vector search ("vector database") to enable efficient similarity searches. This is particularly useful for AI/ML/RAG applications, e.g. image, audio, or text similarity. Other use cases include semantic search or recommendation engines. See https://docs.objectbox.io/ann-vector-search for details.

• Adjusting the version number to match the core version (4.0); we will be aligning on major versions from now on.

• Made closing the store more robust; e.g. it waits for ongoing queries and transactions to finish (please still ensure to clean up properly on your side, this is an additional safety net)

• Made Box API more robust when racing against store closing

• Add "vectorsearch-cities" example

0.21.0 (2024-02-13)

• In-memory databases (simply provide a "memory:" prefixed "directory")

Sync:

• New client/server statistics API

• New server API to enable authenticators

• Sync server: support for sync permissions, blocks client updates with no write permission

• Added sync-level login/write permissions for Admin Users DB and Web-UI

• New authenticator "ObjectBox Admin" with support for authorization

• New client API for username/password credentials

• New client-side error listener API; initially reports "receive-only" downgrade due to no write permissions.

0.20.0 (2023-12-11)

• Added OBXFeature_Backup to query for the feature's availability

• Internal: added a DB store abstraction layer (another announcement about this will follow)

• Tree API: fix for meta IDs vs. IDs

• Various internal improvements

Sync

• Sync clients may now supply multiple URLs; for each connection attempt a random one is chosen. This allows for client-side load balancing and failover with an ObjectBox Sync cluster.

0.19.0 (2023-09-04)

• New K/V validation option on opening the store

• Additions cursor API: get current ID, ID-based seeks (seek to first ID, seek to next ID)

• Support scalar vector types with basic queries (APIs only, no generator support)

• Various tree API improvements, e.g. introspection

• Minor API clean up: e.g. using int types for bit flags not enums

• Fixes query link condition in combination with some "or" conditions

• Fixes query "less" condition for case-sensitive strings with value indexes (default is hashed index)

• Updated Linux toolchain; now requires glibc 2.28 or higher (and GLIBCXX_3.4.25); e.g. the following minium versions are fine: Debian Buster 10 (2019), Ubuntu 20.04, RHEL 8 (2019)

• Various internal improvements

• Sync: various additions and improvements (client and server)

0.18.1 (2023-01-30)

Recommended bugfix release; please update.

• Fixes "Could not put (-30786)", which may occur in some corner cases on some platforms.

0.18.0 (2022-10-31)

• Date properties can now be tagged as expiration time; which can be then be easily evicted

• Tree API: various additions and improvements, e.g. OBXTreeOptionFlags to configure the tree behavior

• New query condition to match objects that have a given number of relations

• New "max data size" store setting

• Enabled stricter compiler settings

• Added stacktraces on errors (Linux only; very lightweight as it uses external addr2line or llvm-symbolizer)

• Added log callback for most important logs

• Consolidated "user data" passing as the last parameter

• Various internal improvements

C++

• Added BoxTypeless, QueryBuilderBase and QueryBase: these can be used without generated code and template types.

• New APIs to get the schema IDs for entity types and properties

• Added two methods to Store to await asynchronous processing

• Added "internal" namespace so that internal members do not spill into the obx namespace

• Move more implementations to OBX_CPP_FILE

Sync

• Custom protocols for Sync: plugin your own messaging protocol, which ObjectBox Sync will run on

• Improvements to run Sync Server with limited disk space (e.g. on small devices)

• Tree Sync improvements; e.g. consolidate conflicts

• WebSockets (sync protocol) is now a feature, which can be turned off (special build version)

• Performance optimizations

0.17.0 (2022-06-15)

• Added a "weak store" API providing weak reference for stores (typically used by background threads)

• Added Store ID API, e.g. getting a store by its ID

• Various internal improvements including minor optimizations for binary size and performance

C++

• New "OBX_CPP_FILE" define to place declarations in a single .cpp/.cc file: improves compilation time and results

• New "Exception" base class for all thrown exceptions

• Various internal improvements, e.g. a "internal" namespace to better distinguish from userland API

0.16.0 (2022-05-06)

• Allow UTF-8 for database directories on Windows (available for other platforms before)

• Various internal improvements

C++

• Promoted Options to a top level class, as nested classes cannot be declared forward

• New #define to disable FlatBuffers includes to simplify new project setup

• Rename Exception to DbException

• Minor improvements

V0.15.2 (2022-02-15)

• Add store cloning

• Fix attaching to a reopened store

V0.15.1 (2022-01-26)

• Fix non-unique indexes triggering unique constraint violations in corner cases (requires at least two unique constraints in an entity and a specific order; introduced in 0.15.0)

• Admin UI now supports multiple sessions to the same host using different ports (session ID via HTTP request)

• Minor performance improvements with hashed indexes

Sync

• Performance improvements for compression and decompression

V0.15.0 (2021-12-09)

• New "Flex" data type that can contain data of various types like integers, floating points, strings, lists and maps

• New query conditions for Flex lists to find a specific element

• New query conditions for Flex maps to find elements with a specific key or key/value pair

• New unique on-conflict strategy: replace conflicting objects (OBXPropertyFlags_UNIQUE_ON_CONFLICT_REPLACE)

• New functions to attach to existing stores using only the file path (in the same process)

• New APIs for ObjectBox Admin, the web based UI (formerly known as Object Browser): obx_admin_*

• Minor performance improvements for indexed access

• Major performance improvements for tree/GraphQL queries

• ARM binaries are now built for minimal size reducing the library size significantly

• New "no_reader_thread_locals" store option

• Enable debug logging (requires a special build)

• API: Type for query offsets and limits was changed from uint64_t to size_t

• API: rarely used obx_txn_mark_success() was removed; use obx_txn_success()

• API: feature checks consolidated to only use obx_has_feature()

• Many internal improvements

• Core version 3.0.1-2021-12-09

Sync

• New API for embedded server mode: obx_sync_server_* (implementation available on request)

Earlier Versions

The changelogs of earlier versions are available as part of the GitHub releases.

Provides native dynamic/shared library (.so/.dylib/.dll)

• Provides C & C++ headers (objectbox.h & objectbox.hpp)

ObjectBox Generator

Check the ObjectBox Generator releases for details.