> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.bigcommerce.com/developer/docs/beta/checkout-extensions/api-reference/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.bigcommerce.com/_mcp/server.

# Checkout Extensions

Checkout Extensions allows developers to customize checkout experiences by extending the BigCommerce-hosted [Optimized One-Page Checkout](/developer/docs/admin/checkout-and-cart/optimized-one-page-checkout). With Checkout Extensions, developers build custom content or UI functionality that brands can install at defined regions in the checkout flow.

> Build amazing commerce solutions powered by the BigCommerce platform


## API Docs

- Beta Checkout Extensions > Extensions [List Extensions](https://docs.bigcommerce.com/developer/docs/beta/checkout-extensions/api-reference/extensions/get-extensions.md)
- Beta Checkout Extensions > Extensions [Create Extension](https://docs.bigcommerce.com/developer/docs/beta/checkout-extensions/api-reference/extensions/add-extension.md)
- Beta Checkout Extensions > Extensions [Get Extension](https://docs.bigcommerce.com/developer/docs/beta/checkout-extensions/api-reference/extensions/get-extension.md)
- Beta Checkout Extensions > Extensions [Update Extension](https://docs.bigcommerce.com/developer/docs/beta/checkout-extensions/api-reference/extensions/update-extension.md)
- Beta Checkout Extensions > Extensions [Delete Extension](https://docs.bigcommerce.com/developer/docs/beta/checkout-extensions/api-reference/extensions/delete-extension.md)

## OpenAPI Specification

The raw OpenAPI 3.1 specification for this API is available at:
- [OpenAPI JSON](https://docs.bigcommerce.com/developer/docs/beta/checkout-extensions/api-reference/openapi.json)
- [OpenAPI YAML](https://docs.bigcommerce.com/developer/docs/beta/checkout-extensions/api-reference/openapi.yaml)