> ## Documentation Index
> Fetch the complete documentation index at: https://docs-staging-quickstart-revamp.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

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

# Embedded Passwordless Login in Native Applications

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 Native 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 Native applications consists of two steps:

* 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 or an SMS with a one-time password.
* Prompt the user for the one-time-use code, and call the `/oauth/token` endpoint to get authentication tokens.

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

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

<CodeGroup>
  ```bash cURL lines
  curl --request POST \
    --url 'https://{yourDomain}/passwordless/start' \
    --header 'content-type: application/json' \
    --data '{"client_id": "{yourClientId}",  "connection": "email",   "email": "USER_EMAIL",  "send": "code"}'
  ```

  ```csharp C# lines
  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}\",  \"connection\": \"email\",   \"email\": \"USER_EMAIL\",  \"send\": \"code\"}", ParameterType.RequestBody);
  IRestResponse response = client.Execute(request);
  ```

  ```go Go lines expandable
  package main

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

  func main() {

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

  	payload := strings.NewReader("{\"client_id\": \"{yourClientId}\",  \"connection\": \"email\",   \"email\": \"USER_EMAIL\",  \"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 lines
  HttpResponse<String> response = Unirest.post("https://{yourDomain}/passwordless/start")
    .header("content-type", "application/json")
    .body("{\"client_id\": \"{yourClientId}\",  \"connection\": \"email\",   \"email\": \"USER_EMAIL\",  \"send\": \"code\"}")
    .asString();
  ```

  ```javascript Node.JS lines
  var axios = require("axios").default;

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

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

  ```obj-c Obj-C lines expandable
  #import <Foundation/Foundation.h>

  NSDictionary *headers = @{ @"content-type": @"application/json" };
  NSDictionary *parameters = @{ @"client_id": @"{yourClientId}",
                                @"connection": @"email",
                                @"email": @"USER_EMAIL",
                                @"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 lines expandable
  $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}\",  \"connection\": \"email\",   \"email\": \"USER_EMAIL\",  \"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 lines
  import http.client

  conn = http.client.HTTPSConnection("")

  payload = "{\"client_id\": \"{yourClientId}\",  \"connection\": \"email\",   \"email\": \"USER_EMAIL\",  \"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 lines
  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}\",  \"connection\": \"email\",   \"email\": \"USER_EMAIL\",  \"send\": \"code\"}"

  response = http.request(request)
  puts response.read_body
  ```

  ```swift Swift lines expandable
  import Foundation

  let headers = ["content-type": "application/json"]
  let parameters = [
    "client_id": "{yourClientId}",
    "connection": "email",
    "email": "USER_EMAIL",
    "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()
  ```
</CodeGroup>

**Send a magic link via email**

<CodeGroup>
  ```bash cURL lines
  curl --request POST \
    --url 'https://{yourDomain}/passwordless/start' \
    --header 'content-type: application/json' \
    --data '{ "client_id": "{yourClientId}", "connection": "email", "email": "USER_EMAIL", "send": "link"}'
  ```

  ```csharp C# lines
  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}\", \"connection\": \"email\", \"email\": \"USER_EMAIL\", \"send\": \"link\"}", ParameterType.RequestBody);
  IRestResponse response = client.Execute(request);
  ```

  ```go Go lines expandable
  package main

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

  func main() {

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

  	payload := strings.NewReader("{ \"client_id\": \"{yourClientId}\", \"connection\": \"email\", \"email\": \"USER_EMAIL\", \"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 lines
  HttpResponse<String> response = Unirest.post("https://{yourDomain}/passwordless/start")
    .header("content-type", "application/json")
    .body("{ \"client_id\": \"{yourClientId}\", \"connection\": \"email\", \"email\": \"USER_EMAIL\", \"send\": \"link\"}")
    .asString();
  ```

  ```javascript Node.JS lines
  var axios = require("axios").default;

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

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

  ```obj-c Obj-C lines expandable
  #import <Foundation/Foundation.h>

  NSDictionary *headers = @{ @"content-type": @"application/json" };
  NSDictionary *parameters = @{ @"client_id": @"{yourClientId}",
                                @"connection": @"email",
                                @"email": @"USER_EMAIL",
                                @"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 lines expandable
  $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}\", \"connection\": \"email\", \"email\": \"USER_EMAIL\", \"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 lines
  import http.client

  conn = http.client.HTTPSConnection("")

  payload = "{ \"client_id\": \"{yourClientId}\", \"connection\": \"email\", \"email\": \"USER_EMAIL\", \"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 lines
  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}\", \"connection\": \"email\", \"email\": \"USER_EMAIL\", \"send\": \"link\"}"

  response = http.request(request)
  puts response.read_body
  ```

  ```swift Swift lines expandable
  import Foundation

  let headers = ["content-type": "application/json"]
  let parameters = [
    "client_id": "{yourClientId}",
    "connection": "email",
    "email": "USER_EMAIL",
    "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()
  ```
</CodeGroup>

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

<CodeGroup>
  ```bash cURL lines
  curl --request POST \
    --url 'https://{yourDomain}/passwordless/start' \
    --header 'content-type: application/json' \
    --data '{ "client_id": "{yourClientId}",  "connection": "sms",  "phone_number": "USER_PHONE_NUMBER", "send": "code"}'
  ```

  ```csharp C# lines
  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}\",  \"connection\": \"sms\",  \"phone_number\": \"USER_PHONE_NUMBER\", \"send\": \"code\"}", ParameterType.RequestBody);
  IRestResponse response = client.Execute(request);
  ```

  ```go Go lines expandable
  package main

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

  func main() {

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

  	payload := strings.NewReader("{ \"client_id\": \"{yourClientId}\",  \"connection\": \"sms\",  \"phone_number\": \"USER_PHONE_NUMBER\", \"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 lines
  HttpResponse<String> response = Unirest.post("https://{yourDomain}/passwordless/start")
    .header("content-type", "application/json")
    .body("{ \"client_id\": \"{yourClientId}\",  \"connection\": \"sms\",  \"phone_number\": \"USER_PHONE_NUMBER\", \"send\": \"code\"}")
    .asString();
  ```

  ```javascript Node.JS lines
  var axios = require("axios").default;

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

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

  ```obj-c Obj-C lines expandable
  #import <Foundation/Foundation.h>

  NSDictionary *headers = @{ @"content-type": @"application/json" };
  NSDictionary *parameters = @{ @"client_id": @"{yourClientId}",
                                @"connection": @"sms",
                                @"phone_number": @"USER_PHONE_NUMBER",
                                @"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 lines expandable
  $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}\",  \"connection\": \"sms\",  \"phone_number\": \"USER_PHONE_NUMBER\", \"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 lines
  import http.client

  conn = http.client.HTTPSConnection("")

  payload = "{ \"client_id\": \"{yourClientId}\",  \"connection\": \"sms\",  \"phone_number\": \"USER_PHONE_NUMBER\", \"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 lines
  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}\",  \"connection\": \"sms\",  \"phone_number\": \"USER_PHONE_NUMBER\", \"send\": \"code\"}"

  response = http.request(request)
  puts response.read_body
  ```

  ```swift Swift lines expandable
  import Foundation

  let headers = ["content-type": "application/json"]
  let parameters = [
    "client_id": "{yourClientId}",
    "connection": "sms",
    "phone_number": "USER_PHONE_NUMBER",
    "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()
  ```
</CodeGroup>

**Authenticate an SMS user**

<CodeGroup>
  ```bash cURL lines
  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}",  "username": "USER_PHONE_NUMBER",  "otp": "code",  "realm": "sms", "audience": "your-api-audience", "scope": "openid profile email"}'
  ```

  ```csharp C# lines
  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}\",  \"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 lines expandable
  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}\",  \"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))

  }
  ```

  ```javascript Node.JS lines
  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}',
      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);
  });
  ```

  ```obj-c Obj-C lines expandable
  #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}",
                                @"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 lines expandable
  $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}\",  \"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 lines
  import http.client

  conn = http.client.HTTPSConnection("")

  payload = "{ \"grant_type\": \"http://auth0.com/oauth/grant-type/passwordless/otp\",  \"client_id\": \"{yourClientId}\",  \"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 lines
  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}\",  \"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 lines expandable
  imimport Foundation

  let headers = ["content-type": "application/json"]
  let parameters = [
    "grant_type": "http://auth0.com/oauth/grant-type/passwordless/otp",
    "client_id": "{yourClientId}",
    "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()
  ```
</CodeGroup>

**Authenticate an Email user**

<CodeGroup>
  ```bash cURL lines
  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}", "username": "USER_EMAIL", "otp": "code", "realm": "email", "audience": "your-api-audience", "scope": "openid profile email"}'
  ```

  ```csharp C# lines
  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}\", \"username\": \"USER_EMAIL\", \"otp\": \"code\", \"realm\": \"email\", \"audience\": \"your-api-audience\", \"scope\": \"openid profile email\"}", ParameterType.RequestBody);
  IRestResponse response = client.Execute(request);
  ```

  ```go Go lines expandable
  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}\", \"username\": \"USER_EMAIL\", \"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 lines
  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}\", \"username\": \"USER_EMAIL\", \"otp\": \"code\", \"realm\": \"email\", \"audience\": \"your-api-audience\", \"scope\": \"openid profile email\"}")
    .asString();
  ```

  ```javascript Node.JS lines
  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}',
      username: 'USER_EMAIL',
      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);
  });
  ```

  ```obj-c Obj-C lines expandable
  #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}",
                                @"username": @"USER_EMAIL",
                                @"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 lines expandable
  $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}\", \"username\": \"USER_EMAIL\", \"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 lines
  import http.client

  conn = http.client.HTTPSConnection("")

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

  response = http.request(request)
  puts response.read_body
  ```

  ```swift Swift lines expandable
  import Foundation

  let headers = ["content-type": "application/json"]
  let parameters = [
    "grant_type": "http://auth0.com/oauth/grant-type/passwordless/otp",
    "client_id": "{yourClientId}",
    "username": "USER_EMAIL",
    "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()
  ```
</CodeGroup>

If you prefer, you can use the Android or iOS SDKs, which wrap this APIs in a platform-friendly way:

* [Lock.Android Passwordless](/docs/libraries/lock-android/lock-android-passwordless)
* [Lock.swift Passwordless](/docs/lock-swift-passwordless)
* [Auth0.Android Passwordless](/docs/auth0-android-passwordless)
* [Auth0.swift Passwordless](/docs/libraries/auth0-swift/auth0-swift-passwordless)

## Customize MFA with Embedded

<Warning>
  Customizable MFA with the Resource Owner Password Grant, Embedded, or Refresh Token flows is in Early Access. 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 your application requests an <Tooltip tip="Access Token: Authorization credential, in the form of an opaque string or JWT, used to access an API." cta="View Glossary" href="/docs/glossary?term=access+token+at+the">access token at the</Tooltip> `oauth/token` endpoint, the returned response includes the `mfa_token` to use the MFA API and the `mfa_requirements` parameter with a list of authenticators your application currently supports:

```json lines
{
  "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" }
    ]
  }
}
```

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
[
  {
    "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).