ObjectBox C and C++ 6.0.0 beta

Lead feature: P2P Mesh Sync

• WebAssembly (WASM): the library is now built as part of releases;
  also updated the Emscripten toolchain, reducing the binary size significantly
• Admin: modernized user interface based on Vue.js 3 and Material Design 3
• Admin: optimized pages now loading faster
• Android: log messages now use the logcat tag "ObjectBox" (previously "Box")
• Breaking: removed previously deprecated functions from the C API:
  • obx_debug_log() and obx_debug_log_enabled(): use obx_log_level_set() and obx_log_level_get() instead
  • obx_qb_contains_key_value_string(): use obx_qb_equals_key_value_string() instead
  • obx_qb_any_equals_string(): use obx_qb_contains_element_string() instead
• Breaking: removed previously deprecated members from the C++ API:
  • Options(OBX_model*) constructor: use Options().model(model) instead
  • Store::debugLog() and Store::debugLogEnabled(): use Store::logLevelSet() and Store::logLevelGet() instead
  • String vector query condition contains(): use containsElement() instead
  • Sync::client(store, url, credentials): use the builder instead,
    e.g. Sync::client(store).url(url).credentials(credentials).build()
• Internal fixes and improvements

Sync

• New Mesh Sync API: peer-to-peer (P2P) synchronization between sync clients without a central server
  • C: configure via obx_mesh_opt_*() and obx_sync_opt_mesh();
    access the running mesh via obx_sync_mesh() and obx_mesh_*()
  • C++: new MeshOptions and Mesh classes, SyncBuilder::mesh() and SyncClient::mesh()
• C++: fixed SyncClient::removeFilterVariable() removing all filter variables instead of the given one
• C++: fixed registering a SyncClientErrorListener (the error callback was bound to the wrong listener object)

Check also docs for details

ObjectBox C and C++ 5.3.2

• Fixed a corner case with "unique replace on conflict" and absent (e.g. null) sync clock value
• Internal fixes and improvements

Check older changelogs

ObjectBox C and C++ 5.3.1

• Critical fix for sync clock handling without preset clock values (null)
• Helper functions to extract timestamps from sync clock values

Check older changelogs

ObjectBox C and C++ 5.3.0

• Change log level at runtime, i.e. obx_log_level_set()/obx_log_level_get()
• New log level "trace" for most internal details
• Log level "verbose" can now be enabled (debug log builds only)
• Breaking: OBXLogLevel enum values changed; recompile with new header if you used these
  (previously 10/20/30/40/50 for Verbose..Error, now 0-10 matching the runtime log level).
• Admin: Status tab "Count and Sizes" and "System and Info" improved

Sync

• Conflict resolution via sync clock and sync precedence (allows last win with custom conflict resolution)
• Fix bad Sync client state after multiple full sync messages were interrupted
• Fix adding indexes to Sync types

Check changelog for details

ObjectBox C and C++ 5.2.0

• Admin: new "Counts and Sizes" view (via Status page) to give an overview over all types their object counts and sizes
• Admin: refresh button for the data view
• Admin: fix reload via browser to stay on the page
• Admin: schema view to display flags as text
• (Minor) performance improvements of HNSW vector search on Linux ARM targets

Sync

• Sync protocol version 10
• Update client sync filters variables when online
• Clients report errors to the server
• Add OBXSyncFlags_SkipInvalidTxOps

See changelog for previous versions.

ObjectBox C and C++ 5.1.0

5.1.0 (2026-01-19)

• Fix for deleting transactions in non-owner threads with open relation cursors
• Admin: the Schema view now shows if external name of types and properties if configured
• Admin: the Schema view now shows the type as text (e.g. "String") instead of the internal type ID
• Internal updates

Sync

• New Sync protocol V8: using new clients also require a server update
• Remove-operations with object content for Sync filters (optional setting; sync flag)
• Introduce options based Sync client creation (new C API)
• Add DebugLogTxLogs sync flag to log TX log processing on the client side
• Add SkipInvalidTxOps sync flag to skip invalid operations in a TX log on the client side;
  errors are logged and the TX is only partially applied.
• Remove superfluous sync listener triggers when sync filters "report updates" (SKIP_TX)
• Sync clients compress earlier: reduces disk storage for outgoing data
• Reworked SSL certificates for Apple platforms
• Removed support for older Sync protocol versions before 2024-09; protocol V5+ is now required

Check changelog for details

ObjectBox C and C++ 5.0.0

User-Specific Data Sync

• Sync filters: define server-side filter expression to sync individual data for each sync user.
  This is also known as "user-specific data sync" and requires Sync clients version 5.0.
• Client variables: clients may define key/value pairs that can be used in sync filters

New supported platform: Windows ARM64

• Besides x86 and x64, ObjectBox for Windows now also supports ARM64

Sync

• Sync clients may now provide certificate locations for SSL (TLS) connections

Fixes

• Fixed clearing 1:N backlinks for IDs larger than 32-bit (setting backlink ID to 0 on the "1" side)
• In-memory with WAL file: improved error handling
• Safeguard against undefined behavior by panicking in rare illegal usage patterns that are not recoverable.
  I.e. deleting a (write) transaction in a non-owner thread cannot be safely handled in any other way.
• Various small improvements and updates under the hood.

Examples

• Make each example self-contained, you can e.g. copy an example's directory as a starting point for your own app
• Add a convenient build.sh script to each example that works the same way across examples,
  e.g. ./build.sh run to build and run the example in one step
• Make sources more readable (refactorings, added additional comments)
• The Task sync example moved to ObjectBox Sync Examples

Check changelog for details

ObjectBox C and C++ 5.0.0 RC

Release candidate.

ObjectBox C and C++ 4.3.1

Bug fix release

• Cursor/Query: deleting a cursor (e.g. in a non-creator thread) waits for any query to finish
• Query: added safety check to detect using a deleted query instance
• Admin: fix displaying some string values twice
• Add a few missing allocation failure checks
• Internal improvements, e.g. updated dependencies and compiler to new major versions

ObjectBox C and C++ 4.3.0

• 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, and more
• Admin: various new features

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

Check changelog for details