> ## Documentation Index
> Fetch the complete documentation index at: https://auth0.generaltranslation.app/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 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()) {
              processedNode = processedNode.replace(new RegExp(key, "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 [processedChildren, setProcessedChildren] = useState(children);
  useEffect(() => {
    let unsubscribe = null;
    function init() {
      unsubscribe = window.autorun(() => {
        let processedChildren = children;
        for (const [key, value] of window.rootStore.variableStore.values.entries()) {
          processedChildren = processedChildren.replace(new RegExp(key, "g"), value);
        }
        setProcessedChildren(processedChildren);
      });
    }
    if (window.rootStore) {
      init();
    } else {
      window.addEventListener("adu:storeReady", init);
    }
    return () => {
      window.removeEventListener("adu:storeReady", init);
      unsubscribe?.();
    };
  }, [children]);
  return <CodeBlock filename={filename} icon={icon} language={language} lines highlight={highlight}>
      {processedChildren}
    </CodeBlock>;
};

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);
  });
  ```

  ```objc Obj-C theme={null}
  #import <Foundation/Foundation.h>

  NSDictionary *headers = @{ @"content-type": @"application/json" };
  NSDictionary *parameters = @{ @"client_id": @"{yourClientId}",
                                @"client_secret": @"{yourClientSecret}",
                                @"connection": @"email",
                                @"email": @"{userEmail}",
                                @"send": @"code" };

  NSData *postData = [NSJSONSerialization dataWithJSONObject:parameters options:0 error:nil];

  NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"https://{yourDomain}/passwordless/start"]
                                                         cachePolicy:NSURLRequestUseProtocolCachePolicy
                                                     timeoutInterval:10.0];
  [request setHTTPMethod:@"POST"];
  [request setAllHTTPHeaderFields:headers];
  [request setHTTPBody:postData];

  NSURLSession *session = [NSURLSession sharedSession];
  NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request
                                              completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
                                                  if (error) {
                                                      NSLog(@"%@", error);
                                                  } else {
                                                      NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *) response;
                                                      NSLog(@"%@", httpResponse);
                                                  }
                                              }];
  [dataTask resume];
  ```

  ```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
  ```

  ```swift Swift theme={null}
  import Foundation

  let headers = ["content-type": "application/json"]
  let parameters = [
    "client_id": "{yourClientId}",
    "client_secret": "{yourClientSecret}",
    "connection": "email",
    "email": "{userEmail}",
    "send": "code"
  ] as [String : Any]

  let postData = JSONSerialization.data(withJSONObject: parameters, options: [])

  let request = NSMutableURLRequest(url: NSURL(string: "https://{yourDomain}/passwordless/start")! as URL,
                                          cachePolicy: .useProtocolCachePolicy,
                                      timeoutInterval: 10.0)
  request.httpMethod = "POST"
  request.allHTTPHeaderFields = headers
  request.httpBody = postData as Data

  let session = URLSession.shared
  let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
    if (error != nil) {
      print(error)
    } else {
      let httpResponse = response as? HTTPURLResponse
      print(httpResponse)
    }
  })

  dataTask.resume()
  ```
</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);
  });
  ```

  ```objc Obj-C theme={null}
  #import <Foundation/Foundation.h>

  NSDictionary *headers = @{ @"content-type": @"application/json" };
  NSDictionary *parameters = @{ @"client_id": @"{yourClientId}",
                                @"client_secret": @"{yourClientSecret}",
                                @"connection": @"email",
                                @"email": @"{userEmail}",
                                @"send": @"link" };

  NSData *postData = [NSJSONSerialization dataWithJSONObject:parameters options:0 error:nil];

  NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"https://{yourDomain}/passwordless/start"]
                                                         cachePolicy:NSURLRequestUseProtocolCachePolicy
                                                     timeoutInterval:10.0];
  [request setHTTPMethod:@"POST"];
  [request setAllHTTPHeaderFields:headers];
  [request setHTTPBody:postData];

  NSURLSession *session = [NSURLSession sharedSession];
  NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request
                                              completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
                                                  if (error) {
                                                      NSLog(@"%@", error);
                                                  } else {
                                                      NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *) response;
                                                      NSLog(@"%@", httpResponse);
                                                  }
                                              }];
  [dataTask resume];
  ```

  ```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
  ```

  ```swift Swift theme={null}
  import Foundation

  let headers = ["content-type": "application/json"]
  let parameters = [
    "client_id": "{yourClientId}",
    "client_secret": "{yourClientSecret}",
    "connection": "email",
    "email": "{userEmail}",
    "send": "link"
  ] as [String : Any]

  let postData = JSONSerialization.data(withJSONObject: parameters, options: [])

  let request = NSMutableURLRequest(url: NSURL(string: "https://{yourDomain}/passwordless/start")! as URL,
                                          cachePolicy: .useProtocolCachePolicy,
                                      timeoutInterval: 10.0)
  request.httpMethod = "POST"
  request.allHTTPHeaderFields = headers
  request.httpBody = postData as Data

  let session = URLSession.shared
  let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
    if (error != nil) {
      print(error)
    } else {
      let httpResponse = response as? HTTPURLResponse
      print(httpResponse)
    }
  })

  dataTask.resume()
  ```
</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);
  });
  ```

  ```objc Obj-C theme={null}
  #import <Foundation/Foundation.h>

  NSDictionary *headers = @{ @"content-type": @"application/json" };
  NSDictionary *parameters = @{ @"client_id": @"{yourClientId}",
                                @"client_secret": @"{yourClientSecret}",
                                @"connection": @"sms",
                                @"phone_number": @"{userPhoneNumber}",
                                @"send": @"code" };

  NSData *postData = [NSJSONSerialization dataWithJSONObject:parameters options:0 error:nil];

  NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"https://{yourDomain}/passwordless/start"]
                                                         cachePolicy:NSURLRequestUseProtocolCachePolicy
                                                     timeoutInterval:10.0];
  [request setHTTPMethod:@"POST"];
  [request setAllHTTPHeaderFields:headers];
  [request setHTTPBody:postData];

  NSURLSession *session = [NSURLSession sharedSession];
  NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request
                                              completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
                                                  if (error) {
                                                      NSLog(@"%@", error);
                                                  } else {
                                                      NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *) response;
                                                      NSLog(@"%@", httpResponse);
                                                  }
                                              }];
  [dataTask resume];
  ```

  ```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
  ```

  ```swift Swift theme={null}
  import Foundation

  let headers = ["content-type": "application/json"]
  let parameters = [
    "client_id": "{yourClientId}",
    "client_secret": "{yourClientSecret}",
    "connection": "sms",
    "phone_number": "{userPhoneNumber}",
    "send": "code"
  ] as [String : Any]

  let postData = JSONSerialization.data(withJSONObject: parameters, options: [])

  let request = NSMutableURLRequest(url: NSURL(string: "https://{yourDomain}/passwordless/start")! as URL,
                                          cachePolicy: .useProtocolCachePolicy,
                                      timeoutInterval: 10.0)
  request.httpMethod = "POST"
  request.allHTTPHeaderFields = headers
  request.httpBody = postData as Data

  let session = URLSession.shared
  let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
    if (error != nil) {
      print(error)
    } else {
      let httpResponse = response as? HTTPURLResponse
      print(httpResponse)
    }
  })

  dataTask.resume()
  ```
</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);
  });
  ```

  ```objc Obj-C theme={null}
  #import <Foundation/Foundation.h>

  NSDictionary *headers = @{ @"content-type": @"application/json" };
  NSDictionary *parameters = @{ @"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" };

  NSData *postData = [NSJSONSerialization dataWithJSONObject:parameters options:0 error:nil];

  NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"https://{yourDomain}/oauth/token"]
                                                         cachePolicy:NSURLRequestUseProtocolCachePolicy
                                                     timeoutInterval:10.0];
  [request setHTTPMethod:@"POST"];
  [request setAllHTTPHeaderFields:headers];
  [request setHTTPBody:postData];

  NSURLSession *session = [NSURLSession sharedSession];
  NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request
                                              completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
                                                  if (error) {
                                                      NSLog(@"%@", error);
                                                  } else {
                                                      NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *) response;
                                                      NSLog(@"%@", httpResponse);
                                                  }
                                              }];
  [dataTask resume];
  ```

  ```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
  ```

  ```swift Swift theme={null}
  import Foundation

  let headers = ["content-type": "application/json"]
  let parameters = [
    "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"
  ] as [String : Any]

  let postData = JSONSerialization.data(withJSONObject: parameters, options: [])

  let request = NSMutableURLRequest(url: NSURL(string: "https://{yourDomain}/oauth/token")! as URL,
                                          cachePolicy: .useProtocolCachePolicy,
                                      timeoutInterval: 10.0)
  request.httpMethod = "POST"
  request.allHTTPHeaderFields = headers
  request.httpBody = postData as Data

  let session = URLSession.shared
  let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
    if (error != nil) {
      print(error)
    } else {
      let httpResponse = response as? HTTPURLResponse
      print(httpResponse)
    }
  })

  dataTask.resume()
  ```
</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);
  });
  ```

  ```objc Obj-C theme={null}
  #import <Foundation/Foundation.h>

  NSDictionary *headers = @{ @"content-type": @"application/json" };
  NSDictionary *parameters = @{ @"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" };

  NSData *postData = [NSJSONSerialization dataWithJSONObject:parameters options:0 error:nil];

  NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"https://{yourDomain}/oauth/token"]
                                                         cachePolicy:NSURLRequestUseProtocolCachePolicy
                                                     timeoutInterval:10.0];
  [request setHTTPMethod:@"POST"];
  [request setAllHTTPHeaderFields:headers];
  [request setHTTPBody:postData];

  NSURLSession *session = [NSURLSession sharedSession];
  NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request
                                              completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
                                                  if (error) {
                                                      NSLog(@"%@", error);
                                                  } else {
                                                      NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *) response;
                                                      NSLog(@"%@", httpResponse);
                                                  }
                                              }];
  [dataTask resume];
  ```

  ```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
  ```

  ```swift Swift theme={null}
  import Foundation

  let headers = ["content-type": "application/json"]
  let parameters = [
    "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"
  ] as [String : Any]

  let postData = JSONSerialization.data(withJSONObject: parameters, options: [])

  let request = NSMutableURLRequest(url: NSURL(string: "https://{yourDomain}/oauth/token")! as URL,
                                          cachePolicy: .useProtocolCachePolicy,
                                      timeoutInterval: 10.0)
  request.httpMethod = "POST"
  request.allHTTPHeaderFields = headers
  request.httpBody = postData as Data

  let session = URLSession.shared
  let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
    if (error != nil) {
      print(error)
    } else {
      let httpResponse = response as? HTTPURLResponse
      print(httpResponse)
    }
  })

  dataTask.resume()
  ```
</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

<Warning>
  Customizable MFA with the Resource Owner Password Grant, Embedded, or Refresh Token flows is in Early Access. By using this feature, you agree to the applicable Free Trial terms in Okta’s [Master Subscription Agreement](https://www.okta.com/legal/). To learn more, read [Product Release Stages](/docs/troubleshoot/product-lifecycle/product-release-stages). To participate in the early access, contact [Auth0 Support](https://support.auth0.com/).
</Warning>

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).