Cloud apps like Google Docs and Trello are popular because they enable real-time collaboration with colleagues, and they make it easy for us to access our work from all of our devices. However, by centralizing data storage on servers, cloud apps also take away ownership and agency from users. If a service shuts down, the software stops functioning, and data created with that software is lost.

In this article we propose “local-first software”: a set of principles for software that enables both collaboration and ownership for users. Local-first ideals include the ability to work offline and collaborate across multiple devices, while also improving the security, privacy, long-term preservation, and user control of data.

We survey existing approaches to data storage and sharing, ranging from email attachments to web apps to Firebase-backed mobile apps, and we examine the trade-offs of each. We look at Conflict-free Replicated Data Types (CRDTs): data structures that are multi-user from the ground up while also being fundamentally local and private. CRDTs have the potential to be a foundational technology for realizing local-first software.

We share some of our findings from developing local-first software prototypes at Ink & Switch over the course of several years. These experiments test the viability of CRDTs in practice, and explore the user interface challenges for this new data model. Lastly, we suggest some next steps for moving towards local-first software: for researchers, for app developers, and a startup opportunity for entrepreneurs.

…in the cloud, ownership of data is vested in the servers, not the users, and so we became borrowers of our own data. The documents created in cloud apps are destined to disappear when the creators of those services cease to maintain them. Cloud services defy long-term preservation. No Wayback Machine can restore a sunsetted web application. The Internet Archive cannot preserve your Google Docs.

In this article we explored a new way forward for software of the future. We have shown that it is possible for users to retain ownership and control of their data, while also benefiting from the features we associate with the cloud: seamless collaboration and access from anywhere. It is possible to get the best of both worlds.

But more work is needed to realize the local-first approach in practice. Application developers can take incremental steps, such as improving offline support and making better use of on-device storage. Researchers can continue improving the algorithms, programming models, and user interfaces for local-first software. Entrepreneurs can develop foundational technologies such as CRDTs and peer-to-peer networking into mature products able to power the next generation of applications.

Motivation: collaboration and ownership
Seven ideals for local-first software
- No spinners: your work at your fingertips
- Your work is not trapped on one device
- The network is optional
- Seamless collaboration with your colleagues
- The Long Now
- Security and privacy by default
- You retain ultimate ownership and control
Existing data storage and sharing models
- How application architecture affects user experience
  - Files and email attachments
  - Web apps: Google Docs, Trello, Figma
  - Dropbox, Google Drive, Box, OneDrive, etc.
  - Git and GitHub
- Developer infrastructure for building apps
  - Web app (thin client)
  - Mobile app with local storage (thick client)
  - Backend-as-a-Service: Firebase, CloudKit, Realm
  - CouchDB
Towards a better future
- CRDTs as a foundational technology
- Ink & Switch prototypes
  - Trello clone
  - Collaborative drawing
  - Media canvas
  - Findings
- How you can help
  - For distributed systems and programming languages researchers
  - For Human-Computer Interaction (HCI) researchers
  - For practitioners
  - Call for startups
Conclusions