> For the complete documentation index, see [llms.txt](https://dev.ubidots.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://dev.ubidots.com/dashboards-and-widgets/custom-metric.md).

# Custom Metric

Build custom dashboard widgets as React apps with the Custom Metric widget and @ubidots/react-html-canvas

## Introduction

The Custom Metric widget lets you build your own dashboard widget when the off-the-shelf widgets don't fit. A Custom Metric widget is a small React app built on [`@ubidots/react-html-canvas`](/sdks/dashboard-runtime-library.md). It renders inside an iframe on the dashboard and talks to the dashboard only through that library: hooks, actions and widget events.

{% hint style="info" %}
Custom Metric is the new version of the [HTML Canvas](/dashboards-and-widgets/html-canvas.md) widget. Use it for new custom widgets.
{% endhint %}

## How to create a Custom Metric widget

Go to a dashboard, click the *Add new widget* button (+) and select *Custom Metric*. Pick the variables the widget shows, then write the widget's code in its code editor, or describe what you want to the AI assistant and let it write the code.

## What a widget can do

A widget works with the dashboard in two directions: what it can **GET** (read) and what it can **EMIT** (drive). See [Dashboard capabilities](/dashboards-and-widgets/custom-metric/dashboard-capabilities.md) for the full list, with the exact shape and a snippet for each item.

* [Project setup](/dashboards-and-widgets/custom-metric/project-setup.md): the files of a widget, how it mounts, and its `manifest.toml`.
* [Layout and CSS](/dashboards-and-widgets/custom-metric/layout-and-css.md): fill the widget at any size.
* [Dashboard capabilities](/dashboards-and-widgets/custom-metric/dashboard-capabilities.md): the widget's data, devices, date range, real-time, dashboard actions and widget-to-widget events.


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