> You are reading the Docusign Developer Documentation. For clean Markdown of any page, append .md to the page URL. > > Documentation indexes by section: > - APIs and SDKs: https://docusign.docs.buildwithfern.com/docs/llms.txt > - Platform 101: https://docusign.docs.buildwithfern.com/platform/llms.txt > - Extension Apps: https://docusign.docs.buildwithfern.com/extension-apps/llms.txt > - Docusign CLI: https://docusign.docs.buildwithfern.com/docusign-cli/llms.txt > > Authentication (OAuth, JWT Grant, M2M): https://docusign.docs.buildwithfern.com/platform/auth > Webhooks and Connect: https://docusign.docs.buildwithfern.com/platform/webhooks > > OpenAPI specifications: https://docusign.docs.buildwithfern.com/openapi.json > MCP server: https://docusign.docs.buildwithfern.com/_mcp/server # How extension apps differ from API integrations > Learn about the differences between extension apps and API integrations. Extension apps and API integrations are types of applications that you can implement to meet your organization’s agreement process requirements. An [extension app](/extension-apps/extension-apps-101) incorporates external functionality into the Docusign agreement process. Each extension app performs one or more tasks, such as archiving a document or verifying customer data. It accomplishes a task by launching requests to an external service, such as Google, Salesforce, or Dropbox, or to your own API. To be used, an extension app must be incorporated into a Docusign [envelope](/docs/esign-rest-api/esign101/concepts/envelopes) or [workflow](/docs/workflow-builder-api/workflow-builder101/workflows) at one or more [extension points](/extension-apps/extension-apps-101/concepts/extensions-and-extension-points#extension-points), such as an envelope field or workflow step. When a recipient completes the envelope field or workflow step, the extension app’s functionality is triggered. An [API integration](/platform/build-integration) is a self-contained application that incorporates Docusign features by making requests to [Docusign APIs](/docs). API integrations can implement a complete, end-to-end agreement process that includes creating and sending documents, as well as any business logic that is applied before, during, or after document processing. Here’s a summary of other differences. | Area | Extension apps | API integrations | | ------------------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | API caller/callee relationship | The Docusign agreement is the caller, and the external API is the callee. An extension app defines the [connection and endpoint details](/extension-apps/extension-apps-101/concepts/extension-app-manifest) that enable a Docusign agreement to call an external API. | The API integration is the caller, and the Docusign API is the callee. | | Business logic | Business logic is implemented in an external platform. An extension app leverages this functionality by calling the external platform endpoints. | API integrations contain all the code required for business processes and calling Docusign APIs. | | Development process | You register extension apps in the Docusign [Developer Console](/extension-apps/developer-console-overview) by [using a guided, form-based process](/extension-apps/build-an-extension-app/register/use-form) or by [constructing a JSON app manifest file](/extension-apps/build-an-extension-app/register/use-manifest). | You create API integrations in your own development environment using your preferred development tools and programming languages. | | Testing | You can [test extension apps](/extension-apps/build-an-extension-app/test) using the Developer Console’s built-in features that validate authorization and endpoint requests and responses. You can also create envelopes and workflows to test end-user functionality. | To test API integrations, you devise and execute a testing process in your development environment. | | Deployment | Before you can use your extension app in production, you must submit it for [Docusign review](/extension-apps/build-an-extension-app/publish). After it has been approved, you can publish it for production use with the click of a button. | API integrations must pass a [go-live](/platform/go-live) process on the Docusign developer environment in order to be promoted to production. You must perform additional configuration on the production environment after the integration is promoted. | | Distribution | You can make extension apps available in the [Docusign App Center](/extension-apps/extension-apps-101/app-center) after they pass a Docusign review. You can make them available to all users or only to users under specific Docusign accounts. | API integrations are typically available only to your organization or customers; you can choose your own distribution method. | ## Next steps * Learn more about [Extension app concepts](/extension-apps/extension-apps-101/concepts). * Get an overview of [Extension app use cases](/extension-apps/extension-apps-101/use-cases). * Find out how to [Build an extension app](/extension-apps/build-an-extension-app).