> 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 # Reference implementations > Learn about how you can use extension app reference implementations to develop your own extension apps. Reference implementations are downloadable GitHub projects that demonstrate how to implement and use various types of [Extension apps](/extension-apps). Several reference implementations are available for you to download, run, and use as a reference for your own extension app development. Each of these reference implementations showcases one category of [extension](/extension-apps/extension-apps-101/supported-extensions). Each reference implementation also includes ready-to-use manifest files configured to work with a hosted version of the app, enabling you to explore the extension’s behavior immediately—no need to download or run the project. The following reference implementations are available on GitHub: * [Connected fields](https://github.com/docusign/extension-app-connected-fields-reference-implementation): This extension enables real-time custom data verification in eSignature envelopes. Unlike data verification extensions that target specific values (like bank accounts or addresses), the connected fields extension can verify any data against your organization’s system of record. [View hosted manifest files for connected fields](https://github.com/docusign/extension-app-connected-fields-reference-implementation/tree/main/manifests/hosted) * [Data IO](https://github.com/docusign/extension-app-data-io-reference-implementation): This extension enables developers to incorporate data reading and writing operations into custom [workflows](/extension-apps/workflows), enabling seamless integration of data exchanges during the signing process. [View hosted manifest files for data IO](https://github.com/docusign/extension-app-data-io-reference-implementation/tree/main/manifests/hosted) * [Data verification](https://github.com/docusign/extension-app-data-verification-reference-implementation): This is a set of extensions that enable real-time validation of critical fields, including bank account details, bank account ownership, business Federal Employer Identification Numbers (FEIN), email addresses, phone numbers, postal addresses, and Social Security numbers. [View hosted manifest files for data verification](https://github.com/docusign/extension-app-data-verification-reference-implementation/tree/main/manifests/hosted) * [File input from cloud storage](https://github.com/docusign/extension-app-file-input-cloud-storage-reference-implementation/): This extension imports agreements from cloud storage into [Docusign Agreement Manager](https://www.docusign.com/products/platform/agreement-manager), a smart repository that uses AI analysis to transform flat, unstructured documents into structured data points. [View hosted manifest files for file input from cloud storage](https://github.com/docusign/extension-app-file-input-cloud-storage-reference-implementation/tree/main/manifests/hosted) * [File output to cloud storage](http://github.com/docusign/extension-app-file-output-cloud-storage-reference-implementation): This extension enables developers to extract agreements completed within [workflows](/extension-apps/workflows) and save them to a cloud storage provider. [View hosted manifest files for file output to cloud storage](https://github.com/docusign/extension-app-file-output-cloud-storage-reference-implementation/tree/main/manifests/hosted) * [File output to system of record](https://github.com/docusign/extension-app-file-output-system-of-record-reference-implementation): This extension enables developers to extract agreements completed within [workflows](/extension-apps/workflows) and save them to a system of record. [View hosted manifest files for file output to system of record](https://github.com/docusign/extension-app-file-output-system-of-record-reference-implementation/tree/main/manifests/hosted) * [File output to tabular format](https://github.com/docusign/extension-app-file-output-tabular-format-reference-implementation): This extension exports data from [steps in an agreement process](https://support.docusign.com/s/document-item?bundleId=yff1696971835267\&topicId=afu1730332596907.html) to tabular format files stored in cloud storage systems. [View hosted manifest files for file output to tabular format](https://github.com/docusign/extension-app-file-output-tabular-format-reference-implementation/tree/main/manifests/hosted) * [Multiple extensions](https://github.com/docusign/extension-app-data-io-and-verification-reference-implementation): This reference implementation demonstrates how to provide more than one feature in a single extension app by including multiple extensions. [View hosted manifest files for the multi-extension reference implementation](https://github.com/docusign/extension-app-data-io-and-verification-reference-implementation/tree/main/manifests/hosted) To use an extension app reference implementation, clone the project files from GitHub and follow the step-by-step instructions provided in the README file located in the root folder of each implementation. These instructions will guide you through configuring your development environment, running the app, setting up a public endpoint, and preparing the example manifest. The README also includes detailed instructions on how to upload an extension app manifest to the Docusign [Developer Console](/extension-apps/developer-console-overview) to start testing the connection and extensions, whether you're using the local project or a hosted manifest file. ## Next steps * See our documentation on [Extension apps](/extension-apps). * Read our blog post describing how you can [Fast-Track Your Extension Apps with Reference Implementations](https://www.docusign.com/blog/developers/fast-track-your-extension-apps-with-reference-implementations). * Watch our YouTube videos on reference implementations: * [How to Set Up a Reference Implementation for Docusign Extension Apps](https://youtu.be/_4p7GWK5aoA?list=PLXpRTgmbu4oqnHn6pusz4riseJHKZ42HW) * [Setting up a Maestro Workflow to Test a Data IO Extension App](https://youtu.be/rIHlS5ZnkuY?feature=shared) * [Testing a Data IO Extension App](https://youtu.be/xwPMUwaZQnA?feature=shared)