---
title: store
description: A small, framework-agnostic state container with auto-tracked derived values and optional built-in persist.
sidebar:
  label: Overview
type: package
package: "@zap-studio/store"
---

`store` is a small, framework-agnostic state container with auto-tracked derived values and simple built-in persist. It works with any framework, or no framework at all.

## Motivation

Zustand's `setState` does a shallow merge by default. This is a problem for nested state. It also has no built-in derived value: every selector runs again from scratch, with no caching.

Jotai's atom model is nice, but `jotai/utils` alone has more than a dozen helper atoms. One simple idea ("a derived value") grew into a large API.

TanStack Store has the best reactive core of the three. It uses an auto-tracked signal graph, so derived values only recompute when a real dependency changes. But `subscribe()` returns an object shaped like RxJS's `Subscription`, not a plain function. It also has no built-in persistence.

`store` takes TanStack's auto-tracked reactivity and Zustand's simple, single-factory style. The public API stays small on purpose: `createStore`, `derive`, and nothing else. No middleware chain, no Provider, no atom zoo.

## Features

- **[One factory per store](/store/getting-started)**, via `createStore(initialState, actionsFactory?, options?)`. Actions are created once, not on every render or every consumer.
- **`get()` is stable** — it returns the same reference across calls, until the state actually changes. Safe to use as a snapshot source for things like React's `useSyncExternalStore`.
- **[`set` takes an updater only](/store/set)**: `set((prev) => partialOrFullState)`. The result is always shallow-merged. There is no `set({ ... })` shortcut, so there is no confusion between "merge" and "replace".
- **[Auto-tracked derived values](/store/derive)**, via `derive(deps, fn)`. The value is cached. It only recomputes when something `fn` actually read last time has changed. `fn` can read from any store, even one not listed in `deps`, and it will still track correctly.
- **Plain unsubscribe functions** — `subscribe(...)` returns `() => void`, not a `Subscription` object.
- **[Simple built-in persist](/store/persist)** — pass `{ persist: { key, storage } }` to `createStore`. `storage` only needs `getItem` and `setItem`, so `localStorage` and `sessionStorage` work as-is; persist is a no-op during SSR without a custom storage adapter.
- **No required runtime dependencies.**
- **Full TypeScript inference** for state, actions, and the values passed into `derive`. You do not need to write generic types by hand.

## Quick Start

```ts
import { createStore } from "@zap-studio/store";

const counter = createStore({ count: 0 }, (set, get) => ({
  increment: () => set((s) => ({ count: s.count + 1 })),
}));

counter.get(); // { count: 0, increment: fn }
counter.getState(); // { count: 0 }

const unsubscribe = counter.subscribe((state) => console.log(state));
counter.get().increment(); // logs { count: 1, increment: fn }
```

## Learn More

- [Getting Started](/store/getting-started) — install and build your first store step by step
- [`set`](/store/set) — the updater-only setter and how shallow merge works
- [`derive`](/store/derive) — auto-tracked, cached derived values
- [Persist](/store/persist) — save and load state through `localStorage`-shaped storage

## Runtime Support

| Runtime            | Minimum version                         |
| ------------------ | --------------------------------------- |
| Node.js            | 18.0.0                                  |
| Bun                | 1.0.0                                   |
| Deno               | 1.42                                    |
| Cloudflare Workers | Any current release                     |
| Browsers           | Chrome/Edge 98, Firefox 97, Safari 15.4 |

The package ships standard ESM only and uses no runtime-specific APIs. Deno 1.42 is the first release that can install packages from JSR (`deno add jsr:@zap-studio/store`).