---
title: Using the Redoc HTML element
---
# Using the Redoc HTML element
## TL;DR final code example
```html
Redoc
```
:::attention Running Redoc locally requires an HTTP server
Loading local OpenAPI definitions is impossible without running a web server because of issues with
[same-origin policy](https://developer.mozilla.org/en-US/docs/Web/Security/Same-origin_policy) and
other security reasons.
:::
### Running Redoc locally
If you want to view your Redoc output locally, you can simulate an HTTP server.
#### Using Redocly CLI
Redocly CLI is an open source command-line tool that includes a command
for simulating an HTTP server to provide a preview of your OpenAPI definition locally.
If you have [Redocly CLI](https://redocly.com/docs/cli/#installation-and-usage) installed, `cd` into your
project directory and run the following command:
```bash
openapi preview-docs openapi.yaml
```
By default, without providing a port, the preview starts on port 8080, and can be accessed at `http://localhost:8080`.
To exit the preview, use `control+C`.
#### Using Python
If you have [Python 3](https://www.python.org/downloads/) installed, `cd` into your
project directory and run the following command:
```python
python3 -m http.server
```
If you have [Python 2](https://www.python.org/downloads/) installed, `cd` into your
project directory and run the following command:
```python
python -m SimpleHTTPServer 8000
```
The output after entering the command provides the local URL where the preview can be accessed.
To exit the preview, use `control-C`.
#### Using Node.js
If you have [Node.js](https://nodejs.org/en/download/) installed, install `http-server`
using the following npm command:
```bash
npm install -g http-server
```
Then, `cd` into your project directory and run the following command:
```node
http-server
```
The output after entering the command provides the local URL where the preview can be accessed.
To exit the preview, use `control-C`.
## Step 1 - Install Redoc
You can install Redoc using one of the following package managers:
- [npm](https://docs.npmjs.com/about-npm)
- [yarn](https://classic.yarnpkg.com/en/docs/getting-started)
:::attention Initialize your package manager
If you do not have a `package.json` file in your project directory,
you need to add one by initializing npm or yarn in your project. Use the command `npm init` for npm,
or `yarn init` for yarn. These initialization commands will lead you through the process
of creating a `package.json` file in your project.
For more information, see
[Creating a package.json file](https://docs.npmjs.com/creating-a-package-json-file)
in the npm documentation or [Yarn init](https://classic.yarnpkg.com/en/docs/cli/init/)
in the yarn documentation.
:::
### Install Redoc with yarn
After navigating to your project directory in your terminal, use the following command:
```bash
yarn add redoc
```
### Install Redoc with npm
After navigating to your project directory in your terminal, use the following command:
```bash
npm i redoc
```
## Step 2 - Reference the Redoc script
You can reference the Redoc script using either a link to the files hosted on a CDN
or the files located in your `node modules` folder.
### CDN link
To reference the Redoc script with a CDN link:
```html
```
### Node modules link
To reference the Redoc script with a node modules link:
```html
```
## Step 3 - Add the element
You can add the element to your HTML page and reference your OpenAPI
definition using the `spec-url` attribute, or you can initialize Redoc using
a globally exposed Redoc object.
### Using the `spec-url` attribute
To add the element with the `spec-url` attribute:
```html
```
#### Examples
```html
```
You can also use a local file (JSON or YAML) in your project, for instance:
```html
```
### Using a Redoc object
To add the element with a globally exposed Redoc object:
```js
Redoc.init(specOrSpecUrl, options, element, callback)
```
- `specOrSpecUrl`: Either a JSON object with the OpenAPI definition or a URL to the
definition in JSON or YAML format.
- `options`: See [options object](https://redocly.com/docs/api-reference-docs/configuration/) reference.
- `element`: DOM element Redoc will be inserted into.
- `callback`(optional): Callback to be called after Redoc has been fully rendered.
It is also called on errors with `error` as the first argument.
#### Examples
```html
```
You can also use a local file (JSON or YAML) in your project, for instance:
```html
```