Local-only calories tracker app

A new paradigm of building apps is coming to the web: Local-first.

One of the key components of a local-first app is having a local data store. PGlite brings the database to the client, allowing you to build apps completely offline.

In this project template we implement the first step before local-first: Local-only.

The project is a Vite app completely on the client. It uses PGlite as local postgres database to make the app work end-to-end on the user device.

Tech stack

The project is built with TanStack Router, which offers complete type-safe routing on the client for React.

A local postgres database is created and managed using PGlite in combination with drizzle as ORM. The app includes the live extension of PGlite, which allow writing reactive queries as normal React hooks.

drizzle is also responsible to manage migrations for local databases using drizzle-kit

The state of the app is managed using xstate. Each functionality is defined in a separate machine. The app makes heavy use of the actor model to combine reusable actors.

The structure and logic of the app is implemented using effect. All the logic is contained in isolated services that are combined inside layers and executed as part of TanStack Router loaders and xstate actors.

All the validation and serialization logic is also implemented using Schema from effect.

The app is styled using tailwindcss (v4). The components are based on react-aria-components, and the styles are applied using a combination of clsx and class-variance-authority. The icons in the app are from lucide-react.

The app can be built using vite. The vite-plugin-pwa plugin generates the required assets and service worker for the app to be installable as a PWA on the device and work offline.

Project structure

The project is an overview of the app implementation. It highlights the most relevant details about each dependency and how to combine them to implement a client-only app.

Each module describes how a specific section of the app is structured:

• Local database: PGlite and drizzle form the data layer, together with Schema from effect
• Live queries: live extension of PGlite to read the database with real-time updates
• Routing: TanStack Router with type-safe routes and loaders
• State management: xstate using the actor model
• UI: react-aria-components in combination with tailwindcss

What's missing to make the app local-first?

For an app to be local-first the implementation must start from the client.

This project defines the first step: making the app independent of the server and completely functional on the client even without internet access.

The last step is multi-device and collaboration support. This could be achieved using a sync engine, which could be added to this project to sync the local database with a other devices.