Open-source alternatives to H2database

MiniOB is an open-source educational relational database kernel designed for learning the internals of database systems. It implements a dual-engine storage architecture combining B+ Tree and LSM-Tree, supports SQL parsing and query execution, and provides transactional processing with multi-version concurrency control. The system communicates with clients using the MySQL wire protocol and includes a vector database extension for storing and querying high-dimensional vectors. The project distinguishes itself through its comprehensive coverage of core database concepts in a single, learnable c

PostgreSQL is an object-relational database management system designed for the persistent storage and retrieval of structured information. It functions as an ACID-compliant database server, utilizing standard query language protocols to maintain data consistency and reliability across large-scale application datasets. The system distinguishes itself through an extensible architecture that allows for the definition of custom data types, operators, and indexing methods. It employs multi-version concurrency control to enable simultaneous read and write operations without blocking, supported by a

LiteDB is a serverless, embedded NoSQL document database for .NET applications. It persists data into a single portable file, functioning as a BSON data store that resides within the application process rather than running as a separate server. The system is ACID compliant, utilizing write-ahead logging to ensure atomic, consistent, isolated, and durable transactions. It includes built-in encryption to provide secure local data storage and protect files on disk from unauthorized access. The project covers object-document mapping to convert classes into document formats, indexed search capabi

MySQL Server is a relational database management system designed to organize and store structured information. It functions as a comprehensive SQL server platform that provides reliable transactional integrity and high-performance query execution for enterprise data management. The system distinguishes itself through a pluggable storage engine architecture that decouples logical query processing from physical data storage, allowing for specialized handling of diverse workloads. It maintains data consistency and high concurrency through multi-version concurrency control and write-ahead logging

redb is an embedded key-value store and ACID-compliant storage engine. It functions as a persistent storage system for saving and retrieving data as key-value pairs within a tree structure. The engine is built as an MVCC transactional database, utilizing multi-version concurrency control to manage simultaneous reads and writes without blocking. It employs a single-writer multi-reader model to ensure data consistency while allowing multiple threads to access the store. The system provides persistent state management and atomic transaction management to prevent data corruption during crashes.

MapDB is an embedded database engine and disk-backed collection library that stores Java collections on disk or off-heap. It functions as a local data processing engine designed to handle datasets that exceed available physical RAM. The project utilizes off-heap data storage to eliminate garbage collection overhead and employs disk overflow caching to balance memory and disk usage. It provides specialized utilities for filtering and analyzing large volumes of local data on a single machine. The system ensures data integrity through ACID-compliant transactions and multi-version concurrency co

Badger is an embeddable key-value store written in Go that provides persistent data storage for byte keys and values. It is a persistent database that utilizes a tiered LSM tree storage model to optimize disk storage and retrieval efficiency. The system features an ACID transaction engine that ensures data integrity through serializable snapshot isolation and multi-version concurrency control. It also provides an encrypted key-value store with data-at-rest encryption and a managed encrypted key registry to secure stored information. The engine covers a broad set of capabilities including hig

Bolt is a single-file embedded key-value store for Go applications. It is an ACID transactional database that organizes data in B+trees on disk to provide efficient sorted key retrieval and range scans. The system uses a memory-mapped model to map the database file directly into the process address space for fast random-access reads. The project distinguishes itself through a multi-version concurrency control architecture that allows multiple simultaneous readers to access a consistent snapshot of data without blocking a writer. It employs a single-writer multi-reader locking model and uses a

Sled is an embedded key-value store and ACID-compliant database designed for high-performance data persistence. It functions as a log-structured storage engine that organizes data using B+ trees to support efficient range queries and prefix scans. The engine implements a zero-copy data store model, utilizing epoch-based reclamation to provide direct references to cached values without memory allocations. It distinguishes itself through a combination of write-ahead logging, page cache optimizations to reduce write amplification on flash storage, and serializable transactions for atomic multi-k

Medoo is a lightweight PHP database abstraction layer and SQL query builder. It serves as a minimal database wrapper that provides a unified API to execute queries across multiple SQL engines, translating PHP method calls into specific database dialects. The project enables multi-dialect SQL interfacing, allowing a single codebase to interact with various backends including MySQL, MariaDB, PostgreSQL, SQLite, MSSQL, Oracle, and Sybase. It uses prepared statement parameterization to prevent injection attacks while maintaining a programmatic approach to constructing complex SQL statements. The

bbolt is an ACID-compliant embedded key-value store for Go applications. It persists all data in a single memory-mapped file on disk, organizing information using B+ trees to facilitate sorted key iteration and efficient range queries. The project distinguishes itself through a hierarchical data organization model, allowing buckets to be nested within other buckets to create a tree-like structure. It employs a single-writer, multi-reader locking mechanism and copy-on-write transactions to ensure serializable isolation and data integrity. The system includes comprehensive data management capa

ToyDB is a distributed SQL database that provides a system for storing and querying data across multiple nodes. It focuses on maintaining strong consistency and fault tolerance through the implementation of a distributed consensus algorithm. The project distinguishes itself by supporting historical data versioning, enabling time-travel queries to retrieve the state of the database from a specific point in the past. It utilizes multi-version concurrency control to manage ACID transactions and ensure data integrity during concurrent operations. The system covers relational data modeling with t

This project is a SQL database abstraction layer that provides a consistent object-oriented interface for interacting with multiple relational database systems. It includes a driver wrapper to standardize connections and result sets, a fluent query builder for constructing portable SQL statements, and a type mapper for converting database-specific data types into native application types and vice versa. The library enables programmatic schema management through a schema manager that can introspect database metadata, model structures as objects, and generate the SQL required to migrate between

This project is a curated collection of academic papers, books, and technical resources designed for studying the architecture and implementation of database management systems. It serves as a comprehensive educational guide for engineers and researchers looking to understand the fundamental principles behind modern data storage and retrieval. The repository distinguishes itself by providing structured learning paths across critical database domains, including the design of persistent storage engines, the mechanics of query optimization, and the complexities of distributed transaction managem

This is a reference implementation library providing a collection of code samples, Transact-SQL scripts, and schemas for SQL Server, Azure SQL, and Azure Synapse. It focuses on providing standardized implementation patterns and reference code for building relational databases and cloud data warehouses. The library distinguishes itself by offering specialized guides and examples for deploying database instances within containerized environments and Azure cloud services. It includes specific reference databases and language extensions for integrating machine learning services and advanced analy

This project is a comprehensive technical interview preparation resource and computer science interview guide. It serves as an educational reference for developers to study core software engineering fundamentals and common coding patterns required for employment screenings. The repository provides detailed guides and references covering data structures and algorithms, networking and security, operating systems, and web development. It specifically focuses on the implementation and complexity analysis of sorting, searching, and graph algorithms. The material encompasses a wide breadth of comp

This is a mobile object database and NoSQL local data store that replaces relational tables with a schema-based model. It functions as a reactive data store, using live object observations and change notifications to trigger automatic user interface refreshes. The system provides built-in mobile cloud data synchronization to keep local datasets consistent with a remote server across multiple devices. It also includes security features for encrypted local storage, protecting sensitive on-disk data using at-rest encryption keys and fine-grained access control. Broad capabilities include object

Presto is a distributed SQL query engine designed for high-performance analytical processing across heterogeneous data sources. It functions as a data federation platform and massively parallel processing engine, allowing users to execute interactive queries against diverse storage systems without requiring data migration. By mapping remote metadata and structures to a unified relational namespace, it enables seamless cross-platform analysis through a standard SQL interface. The engine distinguishes itself through a pluggable connector architecture and a shared-nothing distributed processing

Mealie is a self-hosted recipe management platform designed for personal data ownership and household meal planning. It functions as a digital kitchen assistant that allows users to import, organize, and digitize culinary content from websites, images, and videos into a structured, searchable database. The application supports multi-user collaboration through household management, enabling shared access to recipes and meal plans while maintaining distinct permissions. The platform distinguishes itself through extensive automation and integration capabilities. It features a programmatic interf

This project is a reactive, offline-first NoSQL database engine designed for JavaScript applications. It provides a robust framework for managing application state by synchronizing data across browsers, mobile devices, and server-side runtimes. By treating local storage as the primary source of truth, it enables applications to remain functional without network connectivity, automatically reconciling changes with remote backends once a connection is restored. The database distinguishes itself through a modular architecture that supports cross-environment synchronization and high-performance d

Pinot is a distributed, columnar analytical database designed for high-concurrency, low-latency query processing. It functions as a real-time OLAP datastore, enabling interactive, user-facing analytics by ingesting and querying massive datasets from both streaming and batch sources. The system architecture relies on a centralized controller for cluster coordination and a distributed segment-based storage model to ensure horizontal scalability. The platform distinguishes itself through a hybrid ingestion pipeline that unifies real-time event streams and historical batch data into a single quer

InsForge is a backend-as-a-service platform that provides an integrated suite of tools for managing relational databases, identity provision, object storage, and serverless compute. It functions as an open-source identity provider and a PostgreSQL database manager featuring integrated vector storage and row-level security. The platform serves as an LLM orchestration gateway, offering a unified endpoint to route requests across various AI providers through an OpenAI-compatible interface. It enables AI-driven application generation and connects AI agents to backend resources using a standardize

AliSQL is a fork of MySQL by Alibaba that extends the relational database management system with enhancements for high performance, scalability, and enterprise-grade availability. It retains the core MySQL identity as a SQL-based database for storing, organizing, and retrieving structured data, while adding optimizations for large-scale transactional and analytical workloads. The project differentiates itself through a set of Alibaba-specific improvements, including a columnar engine for accelerating analytical queries directly on MySQL tables, and a distributed, shared-nothing NDB Cluster en

ihp is a type-safe web framework and full-stack application orchestrator designed for PostgreSQL. It functions as a server-side rendering framework and a type-safe ORM that automatically generates record types from SQL schemas to ensure compile-time query validation. The platform distinguishes itself by verifying routing, database queries, and templates at compile time to prevent runtime crashes. It implements real-time web interfaces using WebSockets for instant data synchronization and employs server-driven hypermedia for partial DOM patching. The framework covers a broad range of integrat

TablePro is a cross-platform database management client designed for browsing, querying, and administering both SQL and NoSQL databases. It functions as a unified workspace that integrates a code-centric SQL editor with schema visualization tools, allowing developers to manage complex data models and execute queries across diverse database engines. The application distinguishes itself through an agentic AI integration layer that connects language models directly to database tools, enabling automated query generation, optimization, and error fixing with configurable approval gates. It features

This project is a social blogging application built with Flask. It provides a platform for user account management, following relationships, and chronological post streams, supported by a PostgreSQL relational database. The application features a multilingual web interface with localized content and date formatting. It is designed as a dockerized web application, utilizing containerization for consistent deployment across different environments. The system integrates a variety of core capabilities, including full-text search with provider abstraction, an asynchronous task worker for backgrou

SQLite is a serverless relational database engine and C-based library that stores data in a single local disk file. It functions as an embedded SQL database, integrating directly into applications without the need for a separate server process. The engine includes specialized capabilities for full-text search indexing and spatial data querying using R-Tree structures for geographic or geometric coordinate ranges. The system provides broad support for SQL data manipulation, database recovery and repair, and change tracking for synchronizing modifications between databases. It also features a