> ## Documentation Index
> Fetch the complete documentation index at: https://docs-dev-docs-event-stream-action-templates.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

> Describes implementing Passwordless authentication with embedded login in regular applications.

# Embedded Passwordless Login in Regular Web Applications

export const ReleaseStageNotice = ({feature, stage, plans, contact, terms}) => {
  const stageTextMap = {
    "beta": "Beta",
    "ea": "Early Access"
  };
  const stageText = stageTextMap[stage] || "a product release stage";
  const prsLink = "/docs/troubleshoot/product-lifecycle/product-release-stages";
  const linkify = (text, url) => {
    return <a href={url} target="_blank" rel="noreferrer" class="link">{text}</a>;
  };
  const includeDetails = (plans, contact, terms) => {
    const hasDetails = terms || plans || contact;
    if (!hasDetails) return null;
    return <span data-as="p">
            {plans && <>This feature is available for {linkify(`${plans} plans`, "https://auth0.com/pricing")}. </>}
            {contact && "To participate, contact " + contact + ". "}
            {terms && <>By using this feature, you agree to the applicable Free Trial terms in Okta's {linkify("Master Subscription Agreement", "https://www.okta.com/legal")}.</>}
        </span>;
  };
  return <Warning>
            <span data-as="p">
                <strong>The {feature} feature is in {linkify(stageText, prsLink)}.</strong>
            </span>

            {includeDetails(plans, contact, terms)}
        </Warning>;
};

export const AuthCodeGroup = ({children, dropdown}) => {
  const [processedChildren, setProcessedChildren] = useState(children);
  useEffect(() => {
    let unsubscribe = null;
    function init() {
      unsubscribe = window.autorun(() => {
        const processChildren = node => {
          if (typeof node === "string") {
            let processedNode = node;
            for (const [key, value] of window.rootStore.variableStore.values.entries()) {
              const escapedKey = key.replaceAll(/[.*+?^${}()|[\]\\]/g, (String.raw)`\$&`);
              processedNode = processedNode.replaceAll(new RegExp(escapedKey, "g"), value);
            }
            return processedNode;
          } else if (Array.isArray(node)) {
            return node.map(processChildren);
          } else if (node && node.props && node.props.children) {
            return {
              ...node,
              props: {
                ...node.props,
                children: processChildren(node.props.children)
              }
            };
          }
          return node;
        };
        setProcessedChildren(processChildren(children));
      });
    }
    if (window.rootStore) {
      init();
    } else {
      window.addEventListener("adu:storeReady", init);
    }
    return () => {
      window.removeEventListener("adu:storeReady", init);
      unsubscribe?.();
    };
  }, [children]);
  return <CodeGroup dropdown={dropdown}>{processedChildren}</CodeGroup>;
};

export const AuthCodeBlock = ({filename, icon, language, highlight, children}) => {
  const [displayText, setDisplayText] = useState(children);
  const [copyText, setCopyText] = useState(children);
  const wrapperRef = React.useRef(null);
  useEffect(() => {
    let unsubscribe = null;
    function init() {
      if (!window.autorun || !window.rootStore) {
        return;
      }
      unsubscribe = window.autorun(() => {
        let processedChildrenForDisplay = children;
        let processedChildrenForCopy = children;
        for (const [key, value] of window.rootStore.variableStore.values.entries()) {
          const escapedKey = key.replaceAll(/[.*+?^${}()|[\]\\]/g, (String.raw)`\$&`);
          let displayValue = value;
          if (key === "{yourClientSecret}" && value !== "{yourClientSecret}") {
            displayValue = value.substring(0, 3) + "*****MASKED*****";
          }
          processedChildrenForDisplay = processedChildrenForDisplay.replaceAll(new RegExp(escapedKey, "g"), displayValue);
          processedChildrenForCopy = processedChildrenForCopy.replaceAll(new RegExp(escapedKey, "g"), value);
        }
        setDisplayText(processedChildrenForDisplay);
        setCopyText(processedChildrenForCopy);
      });
    }
    if (window.rootStore) {
      init();
    } else {
      window.addEventListener("adu:storeReady", init);
    }
    return () => {
      window.removeEventListener("adu:storeReady", init);
      unsubscribe?.();
    };
  }, [children]);
  useEffect(() => {
    if (!wrapperRef.current) return;
    const originalWriteText = navigator.clipboard.writeText.bind(navigator.clipboard);
    let isOverriding = false;
    const handleClick = e => {
      const button = e.target.closest('[data-testid="copy-code-button"]');
      if (!button || !wrapperRef.current.contains(button)) return;
      isOverriding = true;
      navigator.clipboard.writeText = text => {
        if (isOverriding) {
          isOverriding = false;
          navigator.clipboard.writeText = originalWriteText;
          return originalWriteText(copyText);
        }
        return originalWriteText(text);
      };
      setTimeout(() => {
        if (isOverriding) {
          isOverriding = false;
          navigator.clipboard.writeText = originalWriteText;
        }
      }, 100);
    };
    const wrapper = wrapperRef.current;
    wrapper.addEventListener('click', handleClick, true);
    return () => {
      wrapper.removeEventListener('click', handleClick, true);
      if (navigator.clipboard.writeText !== originalWriteText) {
        navigator.clipboard.writeText = originalWriteText;
      }
    };
  }, [copyText]);
  return <div ref={wrapperRef}>
      <CodeBlock filename={filename} icon={icon} language={language} lines highlight={highlight}>
        {displayText}
      </CodeBlock>
    </div>;
};

To use the Embedded <Tooltip tip="Passwordless: Form of authentication that does not rely on a password as the first factor." cta="View Glossary" href="/docs/glossary?term=Passwordless">Passwordless</Tooltip> APIs in Regular Web Applications, make sure you enable the **Passwordless OTP** grant at [Auth0 Dashboard > Applications > Applications](https://manage.auth0.com/#/applications) in your application's settings under **Advanced Settings** > **Grant Types**.

Passwordless authentication for Regular Web Applications consists of two steps:

1. Capture the user identifier in your application (the user's email or phone number) and invoke the `/passwordless/start` endpoint to initiate the passwordless flow. The user will get an email, an SMS with a one-time-use code, or a magic link.
2. If you did not send a magic link, prompt the user for the one-time-use code, and call the `/oauth/token` endpoint to get authentication tokens.

Note that when using magic links, you don't need to call `/oauth/token`. The user will click the magic link and be redirected to the application's callback URL.

Below, we list a few code snippets that can be used to call these API endpoints for different scenarios.

**Send a one-time-use code via email**

<AuthCodeGroup>
  ```bash cURL theme={null}
  curl --request POST \
    --url 'https://{yourDomain}/passwordless/start' \
    --header 'content-type: application/json' \
    --data '{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "email", "email": "{userEmail}","send": "code"}'
  ```

  ```csharp C# theme={null}
  var client = new RestClient("https://{yourDomain}/passwordless/start");
  var request = new RestRequest(Method.POST);
  request.AddHeader("content-type", "application/json");
  request.AddParameter("application/json", "{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "email", "email": "{userEmail}","send": "code"}", ParameterType.RequestBody);
  IRestResponse response = client.Execute(request);
  ```

  ```go Go theme={null}
  package main

  import (
  	"fmt"
  	"strings"
  	"net/http"
  	"io/ioutil"
  )

  func main() {

  	url := "https://{yourDomain}/passwordless/start"

  	payload := strings.NewReader("{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "email", "email": "{userEmail}","send": "code"}")

  	req, _ := http.NewRequest("POST", url, payload)

  	req.Header.Add("content-type", "application/json")

  	res, _ := http.DefaultClient.Do(req)

  	defer res.Body.Close()
  	body, _ := ioutil.ReadAll(res.Body)

  	fmt.Println(res)
  	fmt.Println(string(body))

  }
  ```

  ```java Java theme={null}
  HttpResponse<String> response = Unirest.post("https://{yourDomain}/passwordless/start")
    .header("content-type", "application/json")
    .body("{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "email", "email": "{userEmail}","send": "code"}")
    .asString();
  ```

  ```javascript Node.JS theme={null}
  var axios = require("axios").default;

  var options = {
    method: 'POST',
    url: 'https://{yourDomain}/passwordless/start',
    headers: {'content-type': 'application/json'},
    data: {
      client_id: '{yourClientId}',
      client_secret: '{yourClientSecret}',
      connection: 'email',
      email: '{userEmail}',
      send: 'code'
    }
  };

  axios.request(options).then(function (response) {
    console.log(response.data);
  }).catch(function (error) {
    console.error(error);
  });
  ```

  ```php PHP theme={null}
  $curl = curl_init();

  curl_setopt_array($curl, [
    CURLOPT_URL => "https://{yourDomain}/passwordless/start",
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_ENCODING => "",
    CURLOPT_MAXREDIRS => 10,
    CURLOPT_TIMEOUT => 30,
    CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
    CURLOPT_CUSTOMREQUEST => "POST",
    CURLOPT_POSTFIELDS => "{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "email", "email": "{userEmail}","send": "code"}",
    CURLOPT_HTTPHEADER => [
      "content-type: application/json"
    ],
  ]);

  $response = curl_exec($curl);
  $err = curl_error($curl);

  curl_close($curl);

  if ($err) {
    echo "cURL Error #:" . $err;
  } else {
    echo $response;
  }
  ```

  ```python Python theme={null}
  import http.client

  conn = http.client.HTTPSConnection("")

  payload = "{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "email", "email": "{userEmail}","send": "code"}"

  headers = { 'content-type': "application/json" }

  conn.request("POST", "/{yourDomain}/passwordless/start", payload, headers)

  res = conn.getresponse()
  data = res.read()

  print(data.decode("utf-8"))
  ```

  ```ruby Ruby theme={null}
  require 'uri'
  require 'net/http'
  require 'openssl'

  url = URI("https://{yourDomain}/passwordless/start")

  http = Net::HTTP.new(url.host, url.port)
  http.use_ssl = true
  http.verify_mode = OpenSSL::SSL::VERIFY_NONE

  request = Net::HTTP::Post.new(url)
  request["content-type"] = 'application/json'
  request.body = "{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "email", "email": "{userEmail}","send": "code"}"

  response = http.request(request)
  puts response.read_body
  ```
</AuthCodeGroup>

**Send a magic link via email**

You need to specify `send: link`.

<AuthCodeGroup>
  ```bash cURL theme={null}
  curl --request POST \
    --url 'https://{yourDomain}/passwordless/start' \
    --header 'content-type: application/json' \
    --data '{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "email", "email": "{userEmail}","send": "link"}'
  ```

  ```csharp C# theme={null}
  var client = new RestClient("https://{yourDomain}/passwordless/start");
  var request = new RestRequest(Method.POST);
  request.AddHeader("content-type", "application/json");
  request.AddParameter("application/json", "{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "email", "email": "{userEmail}","send": "link"}", ParameterType.RequestBody);
  IRestResponse response = client.Execute(request);
  ```

  ```go Go theme={null}
  package main

  import (
  	"fmt"
  	"strings"
  	"net/http"
  	"io/ioutil"
  )

  func main() {

  	url := "https://{yourDomain}/passwordless/start"

  	payload := strings.NewReader("{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "email", "email": "{userEmail}","send": "link"}")

  	req, _ := http.NewRequest("POST", url, payload)

  	req.Header.Add("content-type", "application/json")

  	res, _ := http.DefaultClient.Do(req)

  	defer res.Body.Close()
  	body, _ := ioutil.ReadAll(res.Body)

  	fmt.Println(res)
  	fmt.Println(string(body))

  }
  ```

  ```java Java theme={null}
  HttpResponse<String> response = Unirest.post("https://{yourDomain}/passwordless/start")
    .header("content-type", "application/json")
    .body("{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "email", "email": "{userEmail}","send": "link"}")
    .asString();
  ```

  ```javascript Node.JS theme={null}
  var axios = require("axios").default;

  var options = {
    method: 'POST',
    url: 'https://{yourDomain}/passwordless/start',
    headers: {'content-type': 'application/json'},
    data: {
      client_id: '{yourClientId}',
      client_secret: '{yourClientSecret}',
      connection: 'email',
      email: '{userEmail}',
      send: 'link'
    }
  };

  axios.request(options).then(function (response) {
    console.log(response.data);
  }).catch(function (error) {
    console.error(error);
  });
  ```

  ```php PHP theme={null}
  $curl = curl_init();

  curl_setopt_array($curl, [
    CURLOPT_URL => "https://{yourDomain}/passwordless/start",
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_ENCODING => "",
    CURLOPT_MAXREDIRS => 10,
    CURLOPT_TIMEOUT => 30,
    CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
    CURLOPT_CUSTOMREQUEST => "POST",
    CURLOPT_POSTFIELDS => "{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "email", "email": "{userEmail}","send": "link"}",
    CURLOPT_HTTPHEADER => [
      "content-type: application/json"
    ],
  ]);

  $response = curl_exec($curl);
  $err = curl_error($curl);

  curl_close($curl);

  if ($err) {
    echo "cURL Error #:" . $err;
  } else {
    echo $response;
  }
  ```

  ```python Python theme={null}
  import http.client

  conn = http.client.HTTPSConnection("")

  payload = "{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "email", "email": "{userEmail}","send": "link"}"

  headers = { 'content-type': "application/json" }

  conn.request("POST", "/{yourDomain}/passwordless/start", payload, headers)

  res = conn.getresponse()
  data = res.read()

  print(data.decode("utf-8"))
  ```

  ```ruby Ruby theme={null}
  require 'uri'
  require 'net/http'
  require 'openssl'

  url = URI("https://{yourDomain}/passwordless/start")

  http = Net::HTTP.new(url.host, url.port)
  http.use_ssl = true
  http.verify_mode = OpenSSL::SSL::VERIFY_NONE

  request = Net::HTTP::Post.new(url)
  request["content-type"] = 'application/json'
  request.body = "{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "email", "email": "{userEmail}","send": "link"}"

  response = http.request(request)
  puts response.read_body
  ```
</AuthCodeGroup>

**Send a one-time-use password via SMS**

<AuthCodeGroup>
  ```bash cURL theme={null}
  curl --request POST \
    --url 'https://{yourDomain}/passwordless/start' \
    --header 'content-type: application/json' \
    --data '{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "sms", "phone_number": "{userPhoneNumber}","send": "code"}'
  ```

  ```csharp C# theme={null}
  var client = new RestClient("https://{yourDomain}/passwordless/start");
  var request = new RestRequest(Method.POST);
  request.AddHeader("content-type", "application/json");
  request.AddParameter("application/json", "{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "sms", "phone_number": "{userPhoneNumber}","send": "code"}", ParameterType.RequestBody);
  IRestResponse response = client.Execute(request);
  ```

  ```go Go theme={null}
  package main

  import (
  	"fmt"
  	"strings"
  	"net/http"
  	"io/ioutil"
  )

  func main() {

  	url := "https://{yourDomain}/passwordless/start"

  	payload := strings.NewReader("{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "sms", "phone_number": "{userPhoneNumber}","send": "code"}")

  	req, _ := http.NewRequest("POST", url, payload)

  	req.Header.Add("content-type", "application/json")

  	res, _ := http.DefaultClient.Do(req)

  	defer res.Body.Close()
  	body, _ := ioutil.ReadAll(res.Body)

  	fmt.Println(res)
  	fmt.Println(string(body))

  }
  ```

  ```java Java theme={null}
  HttpResponse<String> response = Unirest.post("https://{yourDomain}/passwordless/start")
    .header("content-type", "application/json")
    .body("{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "sms", "phone_number": "{userPhoneNumber}","send": "code"}")
    .asString();
  ```

  ```javascript Node.JS theme={null}
  var axios = require("axios").default;

  var options = {
    method: 'POST',
    url: 'https://{yourDomain}/passwordless/start',
    headers: {'content-type': 'application/json'},
    data: {
      client_id: '{yourClientId}',
      client_secret: '{yourClientSecret}',
      connection: 'sms',
      phone_number: '{userPhoneNumber}',
      send: 'code'
    }
  };

  axios.request(options).then(function (response) {
    console.log(response.data);
  }).catch(function (error) {
    console.error(error);
  });
  ```

  ```php PHP theme={null}
  $curl = curl_init();

  curl_setopt_array($curl, [
    CURLOPT_URL => "https://{yourDomain}/passwordless/start",
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_ENCODING => "",
    CURLOPT_MAXREDIRS => 10,
    CURLOPT_TIMEOUT => 30,
    CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
    CURLOPT_CUSTOMREQUEST => "POST",
    CURLOPT_POSTFIELDS => "{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "sms", "phone_number": "{userPhoneNumber}","send": "code"}",
    CURLOPT_HTTPHEADER => [
      "content-type: application/json"
    ],
  ]);

  $response = curl_exec($curl);
  $err = curl_error($curl);

  curl_close($curl);

  if ($err) {
    echo "cURL Error #:" . $err;
  } else {
    echo $response;
  }
  ```

  ```python Python theme={null}
  import http.client

  conn = http.client.HTTPSConnection("")

  payload = "{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "sms", "phone_number": "{userPhoneNumber}","send": "code"}"

  headers = { 'content-type': "application/json" }

  conn.request("POST", "/{yourDomain}/passwordless/start", payload, headers)

  res = conn.getresponse()
  data = res.read()

  print(data.decode("utf-8"))
  ```

  ```ruby Ruby theme={null}
  require 'uri'
  require 'net/http'
  require 'openssl'

  url = URI("https://{yourDomain}/passwordless/start")

  http = Net::HTTP.new(url.host, url.port)
  http.use_ssl = true
  http.verify_mode = OpenSSL::SSL::VERIFY_NONE

  request = Net::HTTP::Post.new(url)
  request["content-type"] = 'application/json'
  request.body = "{"client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "connection": "sms", "phone_number": "{userPhoneNumber}","send": "code"}"

  response = http.request(request)
  puts response.read_body
  ```
</AuthCodeGroup>

**Authenticate an SMS user**

<AuthCodeGroup>
  ```bash cURL theme={null}
  curl --request POST \
    --url 'https://{yourDomain}/oauth/token' \
    --header 'content-type: application/json' \
    --data '{"grant_type": "http://auth0.com/oauth/grant-type/passwordless/otp", "client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "username": "USER_PHONE_NUMBER", "otp": "code", "realm": "sms", "audience": "your-api-audience","scope": "openid profile email"}'
  ```

  ```csharp C# theme={null}
  var client = new RestClient("https://{yourDomain}/oauth/token");
  var request = new RestRequest(Method.POST);
  request.AddHeader("content-type", "application/json");
  request.AddParameter("application/json", "{"grant_type": "http://auth0.com/oauth/grant-type/passwordless/otp", "client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "username": "USER_PHONE_NUMBER", "otp": "code", "realm": "sms", "audience": "your-api-audience","scope": "openid profile email"}", ParameterType.RequestBody);
  IRestResponse response = client.Execute(request);
  ```

  ```go Go theme={null}
  package main

  import (
  	"fmt"
  	"strings"
  	"net/http"
  	"io/ioutil"
  )

  func main() {

  	url := "https://{yourDomain}/oauth/token"

  	payload := strings.NewReader("{"grant_type": "http://auth0.com/oauth/grant-type/passwordless/otp", "client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "username": "USER_PHONE_NUMBER", "otp": "code", "realm": "sms", "audience": "your-api-audience","scope": "openid profile email"}")

  	req, _ := http.NewRequest("POST", url, payload)

  	req.Header.Add("content-type", "application/json")

  	res, _ := http.DefaultClient.Do(req)

  	defer res.Body.Close()
  	body, _ := ioutil.ReadAll(res.Body)

  	fmt.Println(res)
  	fmt.Println(string(body))

  }
  ```

  ```java Java theme={null}
  HttpResponse<String> response = Unirest.post("https://{yourDomain}/oauth/token")
    .header("content-type", "application/json")
    .body("{"grant_type": "http://auth0.com/oauth/grant-type/passwordless/otp", "client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "username": "USER_PHONE_NUMBER", "otp": "code", "realm": "sms", "audience": "your-api-audience","scope": "openid profile email"}")
    .asString();
  ```

  ```javascript Node.JS theme={null}
  var axios = require("axios").default;

  var options = {
    method: 'POST',
    url: 'https://{yourDomain}/oauth/token',
    headers: {'content-type': 'application/json'},
    data: {
      grant_type: 'http://auth0.com/oauth/grant-type/passwordless/otp',
      client_id: '{yourClientId}',
      client_secret: '{yourClientSecret}',
      username: 'USER_PHONE_NUMBER',
      otp: 'code',
      realm: 'sms',
      audience: 'your-api-audience',
      scope: 'openid profile email'
    }
  };

  axios.request(options).then(function (response) {
    console.log(response.data);
  }).catch(function (error) {
    console.error(error);
  });
  ```

  ```php PHP theme={null}
  $curl = curl_init();

  curl_setopt_array($curl, [
    CURLOPT_URL => "https://{yourDomain}/oauth/token",
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_ENCODING => "",
    CURLOPT_MAXREDIRS => 10,
    CURLOPT_TIMEOUT => 30,
    CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
    CURLOPT_CUSTOMREQUEST => "POST",
    CURLOPT_POSTFIELDS => "{"grant_type": "http://auth0.com/oauth/grant-type/passwordless/otp", "client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "username": "USER_PHONE_NUMBER", "otp": "code", "realm": "sms", "audience": "your-api-audience","scope": "openid profile email"}",
    CURLOPT_HTTPHEADER => [
      "content-type: application/json"
    ],
  ]);

  $response = curl_exec($curl);
  $err = curl_error($curl);

  curl_close($curl);

  if ($err) {
    echo "cURL Error #:" . $err;
  } else {
    echo $response;
  }
  ```

  ```python Python theme={null}
  import http.client

  conn = http.client.HTTPSConnection("")

  payload = "{"grant_type": "http://auth0.com/oauth/grant-type/passwordless/otp", "client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "username": "USER_PHONE_NUMBER", "otp": "code", "realm": "sms", "audience": "your-api-audience","scope": "openid profile email"}"

  headers = { 'content-type': "application/json" }

  conn.request("POST", "/{yourDomain}/oauth/token", payload, headers)

  res = conn.getresponse()
  data = res.read()

  print(data.decode("utf-8"))
  ```

  ```ruby Ruby theme={null}
  require 'uri'
  require 'net/http'
  require 'openssl'

  url = URI("https://{yourDomain}/oauth/token")

  http = Net::HTTP.new(url.host, url.port)
  http.use_ssl = true
  http.verify_mode = OpenSSL::SSL::VERIFY_NONE

  request = Net::HTTP::Post.new(url)
  request["content-type"] = 'application/json'
  request.body = "{"grant_type": "http://auth0.com/oauth/grant-type/passwordless/otp", "client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "username": "USER_PHONE_NUMBER", "otp": "code", "realm": "sms", "audience": "your-api-audience","scope": "openid profile email"}"

  response = http.request(request)
  puts response.read_body
  ```
</AuthCodeGroup>

**Authenticate an Email user**

<AuthCodeGroup>
  ```bash cURL theme={null}
  curl --request POST \
    --url 'https://{yourDomain}/oauth/token' \
    --header 'content-type: application/json' \
    --data '{"grant_type": "http://auth0.com/oauth/grant-type/passwordless/otp", "client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "username": "{userPhoneNumber}", "otp": "code", "realm": "email", "audience": "your-api-audience", "scope": "openid profile email"}'
  ```

  ```csharp C# theme={null}
  var client = new RestClient("https://{yourDomain}/oauth/token");
  var request = new RestRequest(Method.POST);
  request.AddHeader("content-type", "application/json");
  request.AddParameter("application/json", "{"grant_type": "http://auth0.com/oauth/grant-type/passwordless/otp", "client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "username": "{userPhoneNumber}", "otp": "code", "realm": "email", "audience": "your-api-audience", "scope": "openid profile email"}", ParameterType.RequestBody);
  IRestResponse response = client.Execute(request);
  ```

  ```go Go theme={null}
  package main

  import (
  	"fmt"
  	"strings"
  	"net/http"
  	"io/ioutil"
  )

  func main() {

  	url := "https://{yourDomain}/oauth/token"

  	payload := strings.NewReader("{"grant_type": "http://auth0.com/oauth/grant-type/passwordless/otp", "client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "username": "{userPhoneNumber}", "otp": "code", "realm": "email", "audience": "your-api-audience", "scope": "openid profile email"}")

  	req, _ := http.NewRequest("POST", url, payload)

  	req.Header.Add("content-type", "application/json")

  	res, _ := http.DefaultClient.Do(req)

  	defer res.Body.Close()
  	body, _ := ioutil.ReadAll(res.Body)

  	fmt.Println(res)
  	fmt.Println(string(body))

  }
  ```

  ```java Java theme={null}
  HttpResponse<String> response = Unirest.post("https://{yourDomain}/oauth/token")
    .header("content-type", "application/json")
    .body("{"grant_type": "http://auth0.com/oauth/grant-type/passwordless/otp", "client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "username": "{userPhoneNumber}", "otp": "code", "realm": "email", "audience": "your-api-audience", "scope": "openid profile email"}")
    .asString();
  ```

  ```javascript Node.JS theme={null}
  var axios = require("axios").default;

  var options = {
    method: 'POST',
    url: 'https://{yourDomain}/oauth/token',
    headers: {'content-type': 'application/json'},
    data: {
      grant_type: 'http://auth0.com/oauth/grant-type/passwordless/otp',
      client_id: '{yourClientId}',
      client_secret: '{yourClientSecret}',
      username: '{userPhoneNumber}',
      otp: 'code',
      realm: 'email',
      audience: 'your-api-audience',
      scope: 'openid profile email'
    }
  };

  axios.request(options).then(function (response) {
    console.log(response.data);
  }).catch(function (error) {
    console.error(error);
  });
  ```

  ```php PHP theme={null}
  $curl = curl_init();

  curl_setopt_array($curl, [
    CURLOPT_URL => "https://{yourDomain}/oauth/token",
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_ENCODING => "",
    CURLOPT_MAXREDIRS => 10,
    CURLOPT_TIMEOUT => 30,
    CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
    CURLOPT_CUSTOMREQUEST => "POST",
    CURLOPT_POSTFIELDS => "{"grant_type": "http://auth0.com/oauth/grant-type/passwordless/otp", "client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "username": "{userPhoneNumber}", "otp": "code", "realm": "email", "audience": "your-api-audience", "scope": "openid profile email"}",
    CURLOPT_HTTPHEADER => [
      "content-type: application/json"
    ],
  ]);

  $response = curl_exec($curl);
  $err = curl_error($curl);

  curl_close($curl);

  if ($err) {
    echo "cURL Error #:" . $err;
  } else {
    echo $response;
  }
  ```

  ```python Python theme={null}
  import http.client

  conn = http.client.HTTPSConnection("")

  payload = "{"grant_type": "http://auth0.com/oauth/grant-type/passwordless/otp", "client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "username": "{userPhoneNumber}", "otp": "code", "realm": "email", "audience": "your-api-audience", "scope": "openid profile email"}"

  headers = { 'content-type': "application/json" }

  conn.request("POST", "/{yourDomain}/oauth/token", payload, headers)

  res = conn.getresponse()
  data = res.read()

  print(data.decode("utf-8"))
  ```

  ```ruby Ruby theme={null}
  require 'uri'
  require 'net/http'
  require 'openssl'

  url = URI("https://{yourDomain}/oauth/token")

  http = Net::HTTP.new(url.host, url.port)
  http.use_ssl = true
  http.verify_mode = OpenSSL::SSL::VERIFY_NONE

  request = Net::HTTP::Post.new(url)
  request["content-type"] = 'application/json'
  request.body = "{"grant_type": "http://auth0.com/oauth/grant-type/passwordless/otp", "client_id": "{yourClientId}", "client_secret": "{yourClientSecret}", "username": "{userPhoneNumber}", "otp": "code", "realm": "email", "audience": "your-api-audience", "scope": "openid profile email"}"

  response = http.request(request)
  puts response.read_body
  ```
</AuthCodeGroup>

**Authenticate a user through a magic link**

When you send a magic link, you don't need to call an API to authenticate the user. Users will click the link and be redirected to the callback URL.

## Setting the auth0-forwarded-for header for rate-limit purposes

The `/passwordless/start` endpoint has a [rate limit](/docs/troubleshoot/customer-support/operational-policies/rate-limit-policy) of 50 requests per hour per IP. If you call the API from the server-side, your backend's IP may easily hit these rate limits. To learn how to address this issue, read the Rate Limiting in Passwordless Endpoints section of [Using Passwordless APIs](/docs/authenticate/passwordless/implement-login/embedded-login/relevant-api-endpoints).

## Customize MFA

<ReleaseStageNotice feature="Customizable MFA with the Resource Owner Password Grant, Embedded, or Refresh Token flows" stage="ea" terms="true" contact="Auth0 Support" />

Customize <Tooltip tip="Multi-factor authentication (MFA): User authentication process that uses a factor in addition to username and password such as a code via SMS." cta="View Glossary" href="/docs/glossary?term=MFA">MFA</Tooltip> with embedded flows. Use the MFA API to allow users to enroll and challenge with factors of their choice that are supported by your application.

When using [Lock for Web](/docs/libraries/lock#2-authenticating-and-getting-user-info), the `oauth/token` endpoint returns the `mfa_required` error and includes the `mfa_token` you need to use the MFA API and `mfa_requirements` parameter with a list of authenticators your application currently supports:

```json lines theme={null}
{
  "error": "mfa_required",
  "error_description": "Multifactor authentication required",
  "mfa_token": "Fe26...Ha",
  "mfa_requirements": {
    "challenge": [
      { "type": "otp" },
      { "type": "push-notification" },
      { "type": "phone" },
      { "type": "recovery-code" }
      { "type": "email"} //can only work with challenge
    ]
  }
}
```

Use the `mfa_token` to call the [`mfa/authenticator`](https://auth0.com/docs/api/authentication/muti-factor-authentication/list-authenticators) endpoint to list all factors the user has enrolled and match the same `type` your application supports. You also need to obtain the matching `authenticator_type` to issue challenges:

```json lines theme={null}
[
  {
    "type": "recovery-code",
    "id": "recovery-code|dev_qpOkGUOxBpw6R16t",
    "authenticator_type": "recovery-code",
    "active": true
  },
  {
    "type": "otp",
    "id": "totp|dev_6NWz8awwC8brh2dN",
    "authenticator_type": "otp",
    "active": true
  }
]
```

Proceed to enforce the MFA challenge by calling the [`request/mfa/challenge`](https://auth0.com/docs/api/authentication/muti-factor-authentication/request-mfa-challenge) endpoint.

Further customize your MFA flow with Auth0 Actions. To learn more, read [Actions Triggers: post-challenge - API Object](/docs/customize/actions/explore-triggers/password-reset-triggers/post-challenge-trigger/post-challenge-api-object).