Local-first Software

What is Local-first Software?

Local-first software prioritizes storing data on the user’s device, ensuring ownership, privacy, and offline functionality. It synchronizes with other devices and the cloud when possible, offering the benefits of cloud-based collaboration without the downsides of centralized data storage.

Let’s take a quick look at how local-first compares to the conventional stack:

For a “traditional” app, the clients are a “thin” layer that depends on the servers for any read/write operations.

Local-first shifts the roles between servers and clients, making clients the primary source of data while servers act as backup and synchronization sources.

How does it work?

Generally, local-first is enabled by two core concepts:

• CRDTs (Conflict-free Replicated Data Types): These data structures allow multiple users to edit documents simultaneously, merging changes without conflicts. You can read more about CRDTs here: Introduction to CRDT.
• Data Synchronization: Changes made offline are synced with other devices and the cloud when a connection is available.

In most cases, end-to-end encryption is required to ensure data security during synchronization.

Why local-first?

• Data Ownership and Privacy: Users have full control over their data, reducing the risk of breaches.
• Offline Functionality: Applications remain fully functional without internet connectivity.
• Performance and Reliability: Local data storage enhances performance and ensures reliability even with poor or no network connections.
• Seamless Collaboration: Enables real-time collaboration and conflict resolution without central servers.

How does it compare to existing models?

• Traditional File Systems and Email Attachments: Offer local data storage but lack real-time collaboration and seamless multi-device synchronization.
• Cloud-based Solutions (e.g., Trello, Google Drive): Improve accessibility and collaboration but centralize control and expose users to data breaches and loss of access.
• Hybrid Models (e.g., Dropbox): Offer local storage with cloud sync but still depend on centralized servers for data availability.

Who is using local-first?

Popular apps that are known to adopt a local-first approach:

• Figma: A design tool that supports real-time collaboration with local-first principles.
• Obsidian: A knowledge base that stores data locally, allowing offline access and synchronization.
• Notion: While primarily cloud-based, it incorporates local-first elements for offline editing and data synchronization.
• Linear: A project management tool that adopts the local-first approach, ensuring data remains accessible and synchronized across devices even without an internet connection.

What’s the catch?

• Complexity of CRDTs: Implementing efficient and scalable CRDTs is technically challenging.
• Security: Ensuring robust encryption and secure data synchronization is critical.
• User Experience: Balancing simplicity and the benefits of local-first architecture in user interfaces.
• Performance Overhead: Managing the performance impact of data synchronization and CRDT operations.

References

1. Local-first software: You own your data, in spite of the cloud (inkandswitch.com)