# Building blocks

> The building blocks a Shoplazza App integrates with — authentication, the REST API, webhooks, App Proxy, and billing — and the order in which to adopt them.

Building blocks are the foundational components you use to integrate with the Shoplazza platform. Each module provides a set of APIs, patterns, and best practices for a specific area of functionality.

Start with **Authentication** — every REST API and Webhook call needs an Access Token. **App Proxy** and **Billing** are independent add-ons; use them only if your app needs them.

- [Authentication](/docs/app/building-blocks/authentication/oauth-flow): OAuth authorization, access scopes, and request signing
- [REST API](/docs/app/building-blocks/rest-api/): API usage, pagination, rate limits, and error handling
- [Webhooks](/docs/app/building-blocks/webhooks/overview): Subscribe to store events and receive real-time notifications
- [App Proxy](/docs/app/building-blocks/app-proxy/overview): Proxy a storefront URL path to your app backend
- [Billing](/docs/app/building-blocks/billing/overview): Charge merchants with one-time or recurring pricing