> 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

# Extension app reference

This section includes schemas for the app manifest and supported extensions and actions.

* [App manifest reference](/extension-apps/extension-app-reference/app-manifest-reference)
* [Extension contracts](/extension-apps/extension-app-reference/extension-contracts)

## Docs

- [App manifest reference](https://developers.docusign.com/extension-apps/extension-app-reference/app-manifest-reference.md): Reference for the app manifest schema.
- [Connection schema](https://developers.docusign.com/extension-apps/extension-app-reference/app-manifest-reference/connection.md): Learn about the schema for the connection object in your extension app manifest.
- [Extension schema](https://developers.docusign.com/extension-apps/extension-app-reference/app-manifest-reference/extension.md): Learn about the extension object schema for your extension app manifest.
- [Action schema](https://developers.docusign.com/extension-apps/extension-app-reference/app-manifest-reference/action.md): Learn about the action object structure for your extension app manifest schema.
- [Troubleshooting manifest errors](https://developers.docusign.com/extension-apps/extension-app-reference/app-manifest-reference/troubleshooting-manifest-errors.md): Learn about common manifest errors and how to resolve them.
- [Extension contracts](https://developers.docusign.com/extension-apps/extension-app-reference/extension-contracts.md): Reference for Docusign extension contracts.
- [Connected fields extension contract reference](https://developers.docusign.com/extension-apps/extension-app-reference/extension-contracts/connected-fields.md): Get the details for connected fields actions, the request formats, and the response formats.
- [Data IO extension contract reference](https://developers.docusign.com/extension-apps/extension-app-reference/extension-contracts/data-io.md): Learn how to implement the Docusign data IO extension.
- [Custom query language reference](https://developers.docusign.com/extension-apps/extension-app-reference/extension-contracts/custom-query-language.md): Learn about Docusign's custom query language for the data I/O extension.
- [Bank account owner verification extension contract reference](https://developers.docusign.com/extension-apps/extension-app-reference/extension-contracts/bank-account-owner-verification.md): Reference information for the bank account owner verification extension.
- [Bank account verification extension contract reference](https://developers.docusign.com/extension-apps/extension-app-reference/extension-contracts/bank-account-verification.md): Learn about the requirements to implement the bank account verification extension.
- [Business FEIN verification extension contract reference](https://developers.docusign.com/extension-apps/extension-app-reference/extension-contracts/business-fein-verification.md): Learn how to use the business FEIN verification extension.
- [Email address verification extension contract reference](https://developers.docusign.com/extension-apps/extension-app-reference/extension-contracts/email-address-verification.md): Learn how to implement the email address verification extension.
- [Phone verification extension contract reference](https://developers.docusign.com/extension-apps/extension-app-reference/extension-contracts/phone-verification.md): Learn how to use the phone verification extension.
- [Postal address verification extension contract reference](https://developers.docusign.com/extension-apps/extension-app-reference/extension-contracts/postal-address-verification.md): Learn about the requirements to implement the postal address verification extension.
- [SSN verification extension contract reference](https://developers.docusign.com/extension-apps/extension-app-reference/extension-contracts/ssn-verification.md): Learn how to use the SSN verification extension.
- [File input cloud storage extension contract reference](https://developers.docusign.com/extension-apps/extension-app-reference/extension-contracts/file-input-cloud-storage.md): Get technical details about file input cloud storage extension requests and responses.
- [File input system of record extension contract reference (beta)](https://developers.docusign.com/extension-apps/extension-app-reference/extension-contracts/file-input-system-of-record.md)
- [File output cloud storage extension contract reference](https://developers.docusign.com/extension-apps/extension-app-reference/extension-contracts/file-output-cloud-storage.md): Get technical details about file output cloud storage extension requests and responses.
- [File output system of record extension contract reference (beta)](https://developers.docusign.com/extension-apps/extension-app-reference/extension-contracts/file-output-system-of-record.md): Get technical details about file output system of record extension requests and responses.
- [File output tabular format extension contract reference](https://developers.docusign.com/extension-apps/extension-app-reference/extension-contracts/file-output-tabular-format.md): Get technical details about file output tabular format extension requests and responses.