Best Free Offline-First Databases

Ditto is an offline-first mobile database that ensures data is always available locally and stays consistent across devices—even in completely disconnected environments. At its core, Ditto uses Conflict-Free Replicated Data Types (CRDTs) to automatically resolve conflicts and guarantee strong eventual consistency, without requiring developers to write custom merge logic. But Ditto doesn’t stop where most offline-first databases do. We go further by making offline-first apps to synchronize even when completely offline. Ditto is the only offline-first database that includes built-in peer-to-peer and mesh networking, allowing devices to sync directly with one another without any cloud or server infrastructure. When a network connection is unavailable, Ditto-enabled devices can discover and sync with nearby peers using Bluetooth, peer-to-peer Wi-Fi, LAN, or cellular—ensuring real-time updates, even in edge environments.

​OrbitDB is a serverless, distributed, peer-to-peer database that utilizes IPFS for data storage and Libp2p Pubsub for automatic synchronization across peers. It employs Merkle-CRDTs to ensure conflict-free database writes and merges, making it suitable for decentralized applications, blockchain integrations, and local-first web apps. OrbitDB offers various database types tailored to different use cases: 'events' for immutable append-only logs, 'documents' for JSON document storage indexed by a specified key, 'keyvalue' for traditional key-value pairs, and 'keyvalue-indexed' for LevelDB-indexed key-value data. All these databases are built atop OpLog, an immutable, cryptographically verifiable, operation-based CRDT structure. The JavaScript implementation supports both browser and Node.js environments, with a Go version maintained by the Berty project.