Local First Showdown: Choosing the Sync Tech for ShelfHelp

2025-11-26

Introduction

Local first apps have become a big deal in the last few years. Users expect their data to work offline, sync fast, feel instant, and never lose progress. For ShelfHelp, my personal book tracker and recommendation tool, I want the entire reading experience to feel smooth on slow networks, spotty hotel WiFi, or even on a plane.

To get there, I explored several local first and near local first platforms: LiveStore, Zero Sync, InstantDB, Convex, ElectricSQL, PowerSync, and PartyKit. Instead of doing a dry side by side, I decided to run this like a tournament. Each tech gets its own entry card with strengths and weaknesses, then the top two go head to head to see which one fits ShelfHelp the best.

LiveStore

LiveStore is a modern local first platform focused on instant UX, structured sync, and offline persistence. It gives you a database that feels like a local cache but syncs across clients with minimal config.

Pros

  • Real offline first model
  • Simple setup
  • Fast optimistic client experience
  • Solid TypeScript DX
  • Works well inside React and Svelte

Cons

  • Still young
  • Smaller ecosystem
  • Limited long term case studies

Zero Sync

Zero Sync is built around the idea that everything should feel instant. You write to a local database first and let the sync happen quietly in the background.

Pros

  • Very strong local first story
  • Offline reads and writes without special setup
  • Sync layer stays out of the way
  • Great performance profile

Cons

  • Focused ecosystem
  • Not as many built in tools as other options
  • May require more custom conflict resolution work

InstantDB

InstantDB tries to make real time apps feel like writing to a normal database. It is designed around instant reactivity, schemas, and relationships.

Pros

  • Real time updates across clients
  • Strong developer experience
  • Good for apps with live interactions
  • Schema driven and predictable

Cons

  • Not fully local first
  • Offline support still growing
  • Harder to use on disconnected devices

Convex

Convex provides a serverless backend with reactive queries. It feels like writing a database that pushes updates to the client in real time.

Pros

  • Fantastic DX
  • Strong real time story
  • Good migrations, storage, and indexing
  • Very simple onboarding

Cons

  • Not local first
  • Writes depend on the network
  • Limited offline support

ElectricSQL

ElectricSQL is a classic local first heavy hitter. It uses CRDTs and SQLite to sync between clients and a central Postgres database.

Pros

  • True offline first
  • SQLite local replica on every client
  • Fast sync performance at scale
  • CRDT conflict resolution
  • Mature model with production usage

Cons

  • Requires running the Electric sync service
  • Heavier setup
  • Best for larger or long term apps

PowerSync

PowerSync is a mobile and web sync engine built around local databases. It focuses on offline support with fast delta based syncing.

Pros

  • Strong offline handling
  • Small and efficient
  • Great for mobile heavy apps
  • Clean separation between local and cloud data

Cons

  • Still early in adoption
  • Limited tooling for complex relationships
  • Fewer examples in the Svelte ecosystem

PartyKit

PartyKit is a platform for real time collaboration and shared state across multiple users. It is not a local first solution on its own, but it pairs well with others.

Pros

  • Great for multiplayer style features
  • Simple real time rooms
  • Low latency updates
  • Good CRDT integration

Cons

  • Not offline first
  • Needs a paired local store
  • More of a companion than a primary sync layer

The Bracket: Who Makes the Finals

Local First Bracket

After running each option through the lens of ShelfHelp, two clear finalists rise to the top:

Zero Sync vs ElectricSQL

Both deliver local first features. Both allow fast interactions. Both minimize latency. They just take different paths to get there.

Final Showdown: Zero Sync vs ElectricSQL

Zero Sync

Zero Sync is lightweight and flexible. It gives ShelfHelp the local first feel with minimal setup. You choose your backend, how conflicts are handled, and how your data is structured. It works great for small to medium sized apps without complex sync rules.

ElectricSQL

ElectricSQL is more robust. It gives me CRDT powered conflict resolution, local SQLite replicas, and a Postgres backed sync service. It is strong for apps with heavy data requirements or large long term growth plans.

Direct Comparison

  • Ease of setup: Zero Sync wins
  • Pure offline support: ElectricSQL wins
  • Strong conflict resolution: ElectricSQL wins
  • Flexibility: Zero Sync wins
  • Future proof scaling: ElectricSQL wins
  • Staying light and simple: Zero Sync wins

This one ends up close. It feels like heavyweight boxing vs lightweight MMA. Both hit hard in their own way.

Final Pick for ShelfHelp

For ShelfHelp and where it is today, Zero Sync fits the best. The app needs instant UX, a light footprint, and a simple sync model. ElectricSQL is something I could upgrade to later if the project grows and Zero Sync is not cutting it.

Zero Sync keeps the dev experience smooth, keeps the UI fast, and lets me stay flexible while the app evolves.