# Introduction

Shop and marketplace apps connect external e-commerce platforms (Shopify, Shopware, Amazon, etc.) to VARIO ERP. They handle bidirectional data synchronisation between the platform and the ERP.

## Architecture

```
┌──────────────┐    webhooks     ┌──────────────┐    API calls    ┌──────────────┐
│   VARIO ERP  │ ──────────────► │   Shop App   │ ──────────────► │   Platform   │
│              │ ◄────────────── │  (your code) │ ◄────────────── │  (Shopware,  │
│              │   ERP API       │              │   Platform API  │   Shopify…)  │
└──────────────┘                 └──────────────┘                 └──────────────┘
```

**Outbound** (ERP → Platform): ERP webhook → queue entry → fetch from ERP → transform → push to platform

**Inbound** (Platform → ERP): Fetch from platform → transform → MultiPart Import into ERP

## What Makes Shop Apps Special

Unlike other VARIO Cloud apps, shop apps:

* **Create sales channels** — each connected shop becomes a sales channel in the ERP
* **Sync product data outbound** — articles, prices, stock levels, and images flow from ERP to the platform
* **Import orders inbound** — orders placed on the platform are imported into the ERP
* **React to ERP webhooks** — changes in the ERP trigger outbound sync via a queue
* **Store per-channel configuration** — each sales channel has its own API credentials, mapping rules, and transfer toggles

## Documentation Structure

| Section                                                                                                                              | Content                                       |
| ------------------------------------------------------------------------------------------------------------------------------------ | --------------------------------------------- |
| [Getting Started](https://github.com/vario-software/dev-guides/blob/main/onlineshops-and-marketplaces-app/getting-started/README.md) | Project structure and first-app tutorial      |
| [Core Concepts](https://github.com/vario-software/dev-guides/blob/main/onlineshops-and-marketplaces-app/core-concepts/README.md)     | Sales channels, data flow, queues, webhooks   |
| [Inbound](https://github.com/vario-software/dev-guides/blob/main/onlineshops-and-marketplaces-app/inbound/README.md)                 | Order, product, and customer import           |
| [Outbound](https://github.com/vario-software/dev-guides/blob/main/onlineshops-and-marketplaces-app/outbound/README.md)               | Product, stock, price, and order-status sync  |
| [Configuration](https://github.com/vario-software/dev-guides/blob/main/onlineshops-and-marketplaces-app/configuration/README.md)     | Channel parameters, mapping, transfer toggles |

{% hint style="info" %}
For general app development topics (manifest, authentication, EAV basics, VQL syntax, local development), see the general VARIO Cloud App documentation. This guide covers only shop-specific patterns.
{% endhint %}