Immutable Ledger Databases

Hyperledger Fabric is a permissioned blockchain framework and enterprise blockchain platform designed for maintaining shared, immutable records of transactions across a network of authorized participants. It provides the infrastructure to build and manage private distributed ledgers that prioritize data confidentiality and scalability. The platform is distinguished by a modular architecture and a pluggable consensus engine. This design allows internal system implementations to be swapped with custom modules to adapt the ledger's behavior and consensus mechanisms to specific technical or industry requirements. The system covers high-level capabilities including distributed consensus implementation for sequencing messages, database-indexed block storage for persisting history, and permissioned access control to restrict data visibility. It utilizes container-based deployment to ensure consistent execution of network components across diverse environments. Development is supported through tools for building project binaries, generating serialization artifacts, and provisioning standardized environments for testing and deployment.

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. It handles concurrent data access and ensures that groups of changes are applied as single units.

CryptoSwift is a cryptography library implemented entirely in the Swift programming language. It provides a collection of standard cryptographic algorithms for encryption, decryption, and hashing without relying on native C libraries or system frameworks. The library supports symmetric and asymmetric encryption, including RSA key generation and signature management. It features authenticated encryption schemes and the ability to generate cryptographic digests for data integrity verification. The toolset covers message authentication codes, secure key derivation from passwords, and data padding. It includes utilities for converting data between binary, string, hexadecimal, and Base64 formats. For large datasets, the library supports incremental data processing via stateful stream processing to manage memory usage.

Hypercore is a distributed append-only logging system designed for maintaining cryptographically signed data streams that are replicated and verified across a network of peers. It provides verifiable data storage using a Merkle tree structure to ensure the integrity and authenticity of information through cryptographic proofs. The project is distinguished by its support for sparse data replication, which allows peers to download only the specific ranges or blocks of a log required for their current needs to reduce bandwidth. It also implements encrypted peer-to-peer messaging and the ability to create read-only log snapshots at specific lengths. The system covers a broad range of capabilities including peer-to-peer data synchronization, log integrity validation, and block-level encryption. It includes tools for managing the local storage lifecycle, such as log truncation and cache management, alongside event listeners for monitoring network connectivity and data updates.

This project is a distributed, document-oriented database system designed to store information in flexible, hierarchical structures. It supports horizontal scaling through automated sharding and maintains high availability across global clusters using a multi-node replication protocol. By executing multi-document operations as atomic units, the system ensures data integrity and consistency across distributed environments. The platform distinguishes itself by integrating advanced vector-based indexing, which enables semantic similarity searches alongside traditional geospatial and lexical queries. It functions as an enterprise-grade data platform, incorporating granular access controls, encryption, and auditing mechanisms to meet the requirements of regulated production environments. These capabilities allow for the management of large-scale datasets while maintaining the flexibility of a schema-less storage model. The system provides a comprehensive suite of tools for database administration, including command-line utilities for infrastructure management, data migration, and performance monitoring. It supports integration with container orchestration platforms and offers standardized client libraries to facilitate connectivity across various programming languages and business intelligence tools.

Jujutsu is a distributed version control engine designed to manage project history through mutable commits and a persistent operation log. By treating the working directory as a mutable commit, it eliminates the need for manual staging areas, allowing users to modify repository history directly without checking out specific branches. The system maintains full compatibility with existing remote repositories, ensuring that local workflows remain interoperable with standard version control ecosystems. A defining characteristic of the project is its conflict-aware architecture, which treats merge conflicts as first-class, persistent objects within the commit history. This approach enables deferred resolution and safer history rewriting, as conflicted states are recorded directly inside commits. Furthermore, the system automates complex tasks such as descendant rebasing and bookmark tracking, ensuring that history remains consistent even when commits are moved or rewritten. The platform provides a functional query language for precise repository navigation, allowing users to filter and traverse commit graphs using set-based operators and reachability analysis. It also supports advanced operational auditing, where every action is recorded in a directed graph to provide full undo capabilities and visibility into concurrent development. These features are supported by a lock-free design that facilitates synchronization across multiple machines and processes. The software is distributed as a command-line tool that includes support for shell completion and configuration of user identity. It integrates with existing infrastructure through native submodule support, file rename tracking, and built-in commands for common code hosting platforms.

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 capabilities via B-tree indexing, and specialized streaming for large binary objects. It also provides a dedicated administrative studio for visual data administration and modification.