# Commerce Integration Layer

The Commerce Integration Layer is a project-scoped backend-for-frontend (BFF) for the commercetools platform that you use to build the integrations your storefront needs. It serves one merged GraphQL API per Project for your storefronts and apps to query, and lets you extend that API with the custom fields, logic, and third-party service calls a storefront requires without standing up your own backend.

The Commerce Integration Layer owns the commercetools trust boundary, so your browser code never handles a commercetools token. It holds each Project's credentials, mints shopper sessions, and resolves shopper reads and writes against the commercetools platform on your behalf. It includes:

- A single, ready-to-use GraphQL API per Project, tailored to your Project's configuration.
- Stateless shopper sessions that keep commercetools tokens off the browser.
- Hosted [extensions](/commerce-integration-layer/schema-extensions.md) that add fields, types, and write-path logic to the API. commercetools runs the extension code, so there's no infrastructure to manage, you push a change and it goes live.
- A per-project router at the public edge that validates and plans each query against your Project's schema.

Together these cover the responsibilities a storefront backend carries in any project. A storefront on the Commerce Integration Layer doesn't need a backend-for-frontend of its own.

## Learn more about the Commerce Integration Layer

- **[Overview](/commerce-integration-layer/overview.md)**

  Learn the concepts and terminology of the Commerce Integration Layer.

- **[Getting started](/commerce-integration-layer/development/get-started.md)**

  Enable your Project, explore the API, and publish your first extension.

- **[Experience API](/commerce-integration-layer/experience-api-overview.md)**

  Understand the Experience API and how sessions authorize it.

## Navigation

- General
  - [Commerce Integration Layer overview](/commerce-integration-layer/overview.md)
  - [GraphQL federation](/commerce-integration-layer/graphql-federation.md)
  - Extensions
    - [Choose an extension type](/commerce-integration-layer/extension-types.md)
    - [Schema extensions](/commerce-integration-layer/schema-extensions.md)
    - [Managed API Extensions](/commerce-integration-layer/managed-api-extensions.md)
  - [Limits](/commerce-integration-layer/limits.md)
- Experience API
  - [Experience API overview](/commerce-integration-layer/experience-api-overview.md)
  - [Hosts and authorization](/commerce-integration-layer/hosts-and-authorization.md)
  - Core Subgraph
    - [Common types](/commerce-integration-layer/experience/common-types.md)
    - [Catalog](/commerce-integration-layer/experience/catalog.md)
    - [Cart](/commerce-integration-layer/experience/cart.md)
    - [Order](/commerce-integration-layer/experience/order.md)
    - [Account](/commerce-integration-layer/experience/account.md)
    - [Shopping List](/commerce-integration-layer/experience/list.md)
    - [B2B](/commerce-integration-layer/experience/b2b.md)
- Development
  - [Get started with the Commerce Integration Layer](/commerce-integration-layer/development/get-started.md)
  - [Write schema extensions](/commerce-integration-layer/development/writing-schema-extensions.md)
  - [Write Managed API Extensions](/commerce-integration-layer/development/writing-managed-api-extensions.md)
  - [Configure and deploy extensions](/commerce-integration-layer/development/configure-and-deploy.md)
  - [Operations and performance](/commerce-integration-layer/development/operations-and-performance.md)
  - [Monitoring and alerting](/commerce-integration-layer/development/monitoring-and-alerting.md)
  - [Best practices](/commerce-integration-layer/development/best-practices.md)
  - Integrations
    - [Checkout integration](/commerce-integration-layer/development/checkout-integration.md)
    - [Identity providers](/commerce-integration-layer/development/identity-providers.md)
    - [Extension authentication](/commerce-integration-layer/development/extension-authentication.md)

## Related pages

- [Search documentation and API specs](/search.md)