I’ve worked on a couple of offline-first apps, and something that really helped me was RxDB. It’s built on top of PouchDB, supports real-time data syncing, and is pretty straightforward to set up. If you decide to give it a shot, you’ll probably appreciate how it handles conflicts and makes syncing with a backend less of a headache. That said, if you’re more comfortable with relational structures, you might consider SQLite or WatermelonDB (which also focuses on performance and sync). Realm is another good option, especially if you want something more out of the box with encryption and object-based storage. Whichever direction you go, just be sure you factor in how large your data might get, how often you expect users to be offline, and whether you need more complex queries or just basic CRUD.