# Lowdb — Lightweight JSON Database for Node.js

> A small, simple JSON file database powered by plain JavaScript objects, ideal for CLIs, small servers, and prototyping.

## Install

Save as a script file and run:

# Lowdb — Lightweight JSON Database for Node.js

## Quick Use
```bash
npm install lowdb
```
```js
import { JSONFilePreset } from 'lowdb/node';

const db = await JSONFilePreset('db.json', { posts: [] });
await db.update(({ posts }) => posts.push({ id: 1, title: 'hello' }));
```

## Introduction
Lowdb is a tiny local JSON database for Node.js, Electron, and browser environments. It reads and writes a plain JSON file, making it easy to inspect, version-control, and debug. When you need persistence without the overhead of a full database server, Lowdb fits in a single dependency.

## What Lowdb Does
- Persists JavaScript objects to a JSON file on disk automatically
- Provides a synchronous and asynchronous API for reads and writes
- Works in Node.js, Electron, and browsers via localStorage adapters
- Supports custom adapters for alternative storage backends
- Requires zero configuration beyond a file path and default data

## Architecture Overview
Lowdb reads the entire JSON file into memory on startup and writes the whole file back on every mutation. The adapter pattern allows swapping the storage layer: JSONFile for Node.js, LocalStorage for browsers, or Memory for testing. Because the data lives in a plain object, any JavaScript operation works directly on it.

## Self-Hosting & Configuration
- Install from npm and import the preset matching your runtime
- No server, daemon, or background process required
- For Electron apps, point the file path to the user data directory
- Use the Memory adapter in test suites to avoid file I/O
- Pair with lodash for richer query and manipulation utilities if needed

## Key Features
- Entire database is a single readable JSON file
- ESM-first with TypeScript types included
- Adapters for file system, localStorage, and in-memory usage
- Atomic writes prevent partial file corruption on crash
- Under 200 lines of source code, easy to audit and extend

## Comparison with Similar Tools
- **SQLite** — full relational engine; Lowdb is simpler when you only need key-value or document storage
- **conf / configstore** — focused on app settings; Lowdb handles arbitrary data models
- **LevelDB** — binary key-value store with better performance; Lowdb trades speed for human-readable files
- **JSON Server** — serves a REST API from a JSON file; Lowdb is an embedded library without HTTP

## FAQ
**Q: Is Lowdb suitable for production APIs?**
A: It works for low-traffic services or tools. For concurrent writes at scale, a proper database engine is a better fit.

**Q: Does it support queries or indexes?**
A: There is no built-in query language. You use plain JavaScript array methods or lodash to filter and sort.

**Q: What happens if the process crashes mid-write?**
A: Lowdb uses atomic file writes (write-to-temp then rename), so the file is never left in a partial state.

**Q: Can multiple processes share the same db.json?**
A: Not safely. Lowdb is designed for single-process use. Use a database server for multi-process access.

## Sources
- https://github.com/typicode/lowdb

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Source: https://tokrepo.com/en/workflows/f6bb1a71-4299-11f1-9bc6-00163e2b0d79
Author: Script Depot