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# Connected Fields API overview

> The Connected Fields API enables you to validate your envelope field data programmatically.

The Connected Fields API lets developers discover custom, partner, or Docusign data models for [extension apps](https://apps.docusign.com/app-center) installed by their accounts. Data models supported today include [seven standard, Docusign-published Data Verification extensions](/extension-apps/extension-app-reference/extension-contracts), and custom models imported using the [Connected fields](/extension-apps/extension-apps-101/supported-extensions/connected-fields) extension type. Connected fields can now be added to envelopes via eSignature REST API by using the output of the Connected Fields API discovery endpoint. Accelerate agreement turnaround times and minimize errors with extension apps that verify and autofill data during signing.

## Places to start

* [Discover connected fields concepts](/docs/connected-fields-api/concepts)
* [See how to verify envelope fields programmatically](/docs/connected-fields-api/send-envelope-with-data-verification-fields)
* [Explore the API Reference](/docs/connected-fields-api/reference)
* [See how to integrate data verification using the Connected Fields API](https://players.brightcove.net/6118377982001/ZhVNgbpMt_default/index.html?videoId=6370599224112)

## Features

#### Seamless access to data models

Easily retrieve the Docusign, partner, or customer-defined data models used by your extension apps. Map and use these models in your eSignature REST API methods.

#### Verify your envelope fields programmatically

Map your envelope fields to your data verification or connected fields extensions to verify the data your recipients enter in real time.

#### Reduce errors and manual input

Improve accuracy, speed, and compliance by verifying and auto-filling recipient fields data during signing.

## Discover more

* [See an example connected fields reference implementation](https://github.com/docusign/extension-app-connected-fields-reference-implementation)
* [See an example data verification reference implementation](https://github.com/docusign/extension-app-data-verification-reference-implementation)
* [Learn about connected fields extension apps](/extension-apps/extension-apps-101/supported-extensions/connected-fields)
* [Watch a video on how to integrate data verification using the Connected Fields API](https://bcove.video/4l51CpM)