Local-first apps
Local-first development is the new kid on the block. Like React and friends, local-first keeps the data in two places, but it does so in a radically different way. In its most essential form, it means running a database in the browser that is kept aligned with the remote datastore via a syncing engine. This kind of thing has been done before with NoSQL databases like CouchDB or with the IndexedDB API, but the modern browser takes it to another level with a Wasm-based database engine, like SQLite.
The user gets a small view of the full data, called a partial replication or a bucket (also called a “shape”). The front-end app interacts directly with that data, and the infrastructure automatically does the work of keeping everything synced. A big benefit here is strong offline support (because the client device is carrying around an actual database).
This is a massive departure from the request-response cycle. In local-first, you don’t fetch data; you subscribe to it. The network becomes a background daemon that reconciles local and remote state using CRDTs (conflict-free replicated data types). CRDTs ensure that if two users edit a task while offline, the merge is seamless rather than messy.
