Object databases

Transparent persistence for Python objects with ACID transactions and history.

Fast on-device object database with built-in HNSW vector search and an optional commercial sync server.

Commercial object database for Java that implements JPA and JDO natively, with no ORM layer.

Smalltalk object database where application code runs inside the transactional object repository.

New Zealand's integrated object database, language and app server for building line-of-business systems.

GigaSpaces' Java in-memory data grid with space-based processing, SQL queries and tiered storage.

Pioneering C++/Java object database that maps persistent objects into virtual memory; now sold by IgniteTech.

Fast Flutter/Dart object database with rich indexed queries, now stalled upstream.

Enterprise object database formerly known as Versant, sold by Actian for complex object models.

In-memory .NET application platform where C# classes are database tables, with no ORM in between.

Genome database system born for C. elegans in 1989, with an object-tree data model; NCBI fork still updated.

McObject's embedded object database for Java and .NET, dual-licensed GPL or commercial.

Deductive object base for metamodeling, built on O-Telos with Datalog rules and unlimited meta-levels.

Objective-C object database with Git-like branching, tree-structured undo and semantic merging built in.

RUN Software's terminology-oriented object database for C++ and .NET, still released on SourceForge.

C# .NET object database with a graph layer (VelocityGraph); last release 11.1.1 in 2022.

Multi-user object database for Squeak and Pharo Smalltalk, written entirely in Smalltalk.

Kellerman Software's commercial embedded object/relational database for .NET, Xamarin and Unity apps.

Ekky Software's embedded C++ object database with B+tree, spatial, full-text and pattern indexes.

Early Java multi-model database mixing documents, graphs and objects, now in patch-only mode.

Multi-model data platform (SQL, objects, globals, vectors) with built-in interoperability, big in healthcare.

French integrated database and app-development platform for desktop, client/server and web apps.

The open-source core of GemFire: a consistent, partitioned in-memory data grid for Java.

Broadcom's commercial in-memory data grid, the enterprise build of Apache Geode.

Simple Android key-value store that persists plain Java/Kotlin objects with Kryo; no SQL, no schemas.

Vector storage and similarity queries built into S3, trading latency for very low cost at scale.

Embedded Java hypergraph database where edges can link any number of atoms, including other edges.

Paradigma Software's multi-engine server: ValentinaDB, DuckDB and SQLite plus report and form servers.

IBM's Java in-memory data grid for caching, HTTP sessions and partitioned object storage; still patched.