In my last post, I mentioned that what makes an app local-first is its ability to keep running even when a connection falters. At first glance, this might look a lot like the offline-first movement that arose alongside the progressive enhancement wave of the mid to late 2010s. But there’s a subtle distinction. Offline-first apps focused primarily on staying functional during network interruptions but the server remained the primary data source. Data in this context is stored locally until a connection is restored, after which the locally stored data is deleted in favor of the remote store. A restored network connection progressively enhanced the experience and syncing only happened when there was new data created during the interim offline period to upload.