---
title: Validate the token
description: Validate Turnstile tokens on your server with the siteverify API.
image: https://edgetunnel-b2h.pages.dev/core-services-preview.png
---

> Documentation Index  
> Fetch the complete documentation index at: https://edgetunnel-b2h.pages.dev/turnstile/llms.txt  
> Use this file to discover all available pages before exploring further. 

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# Validate the token

Learn how to securely validate Turnstile tokens on your server using the Siteverify API.

Mandatory server-side validation

You must call the Siteverify API to complete your Turnstile implementation. The client-side widget alone does not protect your forms.

Server-side validation is required because:

* **Tokens can be forged.** An attacker can submit any string to your form endpoint without completing a challenge.
* **Tokens expire.** Each token is valid for 300 seconds (5 minutes) after generation.
* **Tokens are single-use.** Each token can only be validated once. A replayed token will be rejected with the `timeout-or-duplicate` error code.

## Process

1. Client generates token: Visitor completes Turnstile challenge on your webpage.
2. Token sent to server: Form submission includes the Turnstile token.
3. Server validates token: Your server calls Cloudflare's Siteverify API.
4. Cloudflare responds: Returns `success` or `failure` and additional data.
5. Server takes action: Allow or reject the original request based on validation.

## Siteverify API overview

**Endpoint**

```shell
POST https://challenges.cloudflare.com/turnstile/v0/siteverify
```

### Request format

The API accepts both `application/x-www-form-urlencoded` and `application/json` requests, but always returns JSON responses.

#### Required parameters

| Parameter        | Required | Description                                             |
| ---------------- | -------- | ------------------------------------------------------- |
| secret           | Yes      | Your widget's secret key from the Cloudflare dashboard  |
| response         | Yes      | The token from the client-side widget                   |
| remoteip         | No       | The visitor's IP address                                |
| idempotency\_key | No       | A UUID you generate to safely retry validation requests |

#### Token characteristics

* Maximum length: 2048 characters
* Validity period: 300 seconds (5 minutes) from generation
* Single use: Each token can only be validated once
* Automatic expiry: Tokens automatically expire and cannot be reused

The validation token issued by Turnstile is valid for five minutes. If a user submits the form after this period, the token is considered expired. In this scenario, the server-side verification API will return a failure, and the `error-codes` field in the response will include `timeout-or-duplicate`.

To ensure a successful validation, the visitor must initiate the request and submit the token to your backend within the five-minute window. Otherwise, the Turnstile widget needs to be refreshed to generate a new token. This can be done using the `turnstile.reset` function.

---

## Basic validation examples

* [  JavaScript ](#tab-panel-11831)
* [  PHP ](#tab-panel-11832)
* [  Python ](#tab-panel-11833)
* [  Java ](#tab-panel-11834)
* [  C# ](#tab-panel-11835)

#### JSON

**JavaScript**

```js
const SECRET_KEY = "your-secret-key";


async function validateTurnstile(token, remoteip) {
  try {
    const response = await fetch(
      "https://challenges.cloudflare.com/turnstile/v0/siteverify",
      {
        method: "POST",
        headers: {
          "Content-Type": "application/json",
        },
        body: JSON.stringify({
          secret: SECRET_KEY,
          response: token,
          remoteip: remoteip,
        }),
      },
    );


    const result = await response.json();
    return result;
  } catch (error) {
    console.error("Turnstile validation error:", error);
    return { success: false, "error-codes": ["internal-error"] };
  }
}
```

#### Form Data

**JavaScript**

```js
const SECRET_KEY = "your-secret-key";


async function validateTurnstile(token, remoteip) {
  const formData = new FormData();
  formData.append("secret", SECRET_KEY);
  formData.append("response", token);
  formData.append("remoteip", remoteip);


  try {
    const response = await fetch(
      "https://challenges.cloudflare.com/turnstile/v0/siteverify",
      {
        method: "POST",
        body: formData,
      },
    );


    const result = await response.json();
    return result;
  } catch (error) {
    console.error("Turnstile validation error:", error);
    return { success: false, "error-codes": ["internal-error"] };
  }
}


// Usage in form handler
async function handleFormSubmission(request) {
  const body = await request.formData();
  const token = body.get("cf-turnstile-response");
  const ip =
    request.headers.get("CF-Connecting-IP") ||
    request.headers.get("X-Forwarded-For") ||
    "unknown";


  const validation = await validateTurnstile(token, ip);


  if (validation.success) {
    // Token is valid - process the form
    console.log("Valid submission from:", validation.hostname);
    return processForm(body);
  } else {
    // Token is invalid - reject the submission
    console.log("Invalid token:", validation["error-codes"]);
    return new Response("Invalid verification", { status: 400 });
  }
}
```

```php
<?php
function validateTurnstile($token, $secret, $remoteip = null) {
    $url = 'https://challenges.cloudflare.com/turnstile/v0/siteverify';


    $data = [
        'secret' => $secret,
        'response' => $token
    ];


    if ($remoteip) {
        $data['remoteip'] = $remoteip;
    }


    $options = [
        'http' => [
            'header' => "Content-type: application/x-www-form-urlencoded\r\n",
            'method' => 'POST',
            'content' => http_build_query($data)
        ]
    ];


    $context = stream_context_create($options);
    $response = file_get_contents($url, false, $context);


    if ($response === FALSE) {
        return ['success' => false, 'error-codes' => ['internal-error']];
    }


    return json_decode($response, true);


}


// Usage
$secret_key = 'your-secret-key';
$token = $_POST['cf-turnstile-response'] ?? '';
$remoteip = $\_SERVER['HTTP_CF_CONNECTING_IP'] ??
$\_SERVER['HTTP_X_FORWARDED_FOR'] ??
$\_SERVER['REMOTE_ADDR'];


$validation = validateTurnstile($token, $secret_key, $remoteip);


if ($validation['success']) {
// Valid token - process form
echo "Form submission successful!";
// Process your form data here
} else {
// Invalid token - show error
echo "Verification failed. Please try again.";
error_log('Turnstile validation failed: ' . implode(', ', $validation['error-codes']));
}
?>
```

**Python**

```python
import requests


def validate_turnstile(token, secret, remoteip=None):
    url = 'https://challenges.cloudflare.com/turnstile/v0/siteverify'


    data = {
        'secret': secret,
        'response': token
    }


    if remoteip:
        data['remoteip'] = remoteip


    try:
        response = requests.post(url, data=data, timeout=10)
        response.raise_for_status()
        return response.json()
    except requests.RequestException as e:
        print(f"Turnstile validation error: {e}")
        return {'success': False, 'error-codes': ['internal-error']}


# Usage with Flask
from flask import Flask, request, jsonify


app = Flask(__name__)
SECRET_KEY = 'your-secret-key'


@app.route('/submit-form', methods=['POST'])
def submit_form():
    token = request.form.get('cf-turnstile-response')
    remoteip = request.headers.get('CF-Connecting-IP') or \
               request.headers.get('X-Forwarded-For') or \
               request.remote_addr


    validation = validate_turnstile(token, SECRET_KEY, remoteip)


    if validation['success']:
        # Valid token - process form
        return jsonify({'status': 'success', 'message': 'Form submitted successfully'})
    else:
        # Invalid token - reject submission
        return jsonify({
            'status': 'error',
            'message': 'Verification failed',
            'errors': validation['error-codes']
        }), 400
```

```java
import org.springframework.web.client.RestTemplate;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;


@Service
public class TurnstileService {
private static final String SITEVERIFY_URL = "https://challenges.cloudflare.com/turnstile/v0/siteverify";
private final String secretKey = "your-secret-key";
private final RestTemplate restTemplate = new RestTemplate();


    public TurnstileResponse validateToken(String token, String remoteip) {
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);


        MultiValueMap<String, String> params = new LinkedMultiValueMap<>();
        params.add("secret", secretKey);
        params.add("response", token);
        if (remoteip != null) {
            params.add("remoteip", remoteip);
        }


        HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<>(params, headers);


        try {
            ResponseEntity<TurnstileResponse> response = restTemplate.postForEntity(
                SITEVERIFY_URL, request, TurnstileResponse.class);
            return response.getBody();
        } catch (Exception e) {
            TurnstileResponse errorResponse = new TurnstileResponse();
            errorResponse.setSuccess(false);
            errorResponse.setErrorCodes(List.of("internal-error"));
            return errorResponse;
        }
    }


}


// Controller usage
@PostMapping("/submit-form")
public ResponseEntity<?> submitForm(
@RequestParam("cf-turnstile-response") String token,
HttpServletRequest request) {


    String remoteip = request.getHeader("CF-Connecting-IP");
    if (remoteip == null) {
        remoteip = request.getHeader("X-Forwarded-For");
    }
    if (remoteip == null) {
        remoteip = request.getRemoteAddr();
    }


    TurnstileResponse validation = turnstileService.validateToken(token, remoteip);


    if (validation.isSuccess()) {
        // Valid token - process form
        return ResponseEntity.ok("Form submitted successfully");
    } else {
        // Invalid token - reject submission
        return ResponseEntity.badRequest()
            .body("Verification failed: " + validation.getErrorCodes());
    }


}
```

```csharp
using System.Text.Json;


public class TurnstileService
{
    private readonly HttpClient _httpClient;
    private readonly string _secretKey = "your-secret-key";
    private const string SiteverifyUrl = "https://challenges.cloudflare.com/turnstile/v0/siteverify";


    public TurnstileService(HttpClient httpClient)
    {
        _httpClient = httpClient;
    }


    public async Task<TurnstileResponse> ValidateTokenAsync(string token, string remoteip = null)
    {
        var parameters = new Dictionary<string, string>
        {
            { "secret", _secretKey },
            { "response", token }
        };


        if (!string.IsNullOrEmpty(remoteip))
        {
            parameters.Add("remoteip", remoteip);
        }


        var postContent = new FormUrlEncodedContent(parameters);


        try
        {
            var response = await _httpClient.PostAsync(SiteverifyUrl, postContent);
            var stringContent = await response.Content.ReadAsStringAsync();


            return JsonSerializer.Deserialize<TurnstileResponse>(stringContent);
        }
        catch (Exception ex)
        {
            return new TurnstileResponse
            {
                Success = false,
                ErrorCodes = new[] { "internal-error" }
            };
        }
    }
}


// Controller usage
[HttpPost("submit-form")]
public async Task<IActionResult> SubmitForm([FromForm] string cfTurnstileResponse)
{
    var remoteip = HttpContext.Request.Headers["CF-Connecting-IP"].FirstOrDefault() ??
                   HttpContext.Request.Headers["X-Forwarded-For"].FirstOrDefault() ??
                   HttpContext.Connection.RemoteIpAddress?.ToString();


    var validation = await _turnstileService.ValidateTokenAsync(cfTurnstileResponse, remoteip);


    if (validation.Success)
    {
        // Valid token - process form
        return Ok("Form submitted successfully");
    }
    else
    {
        // Invalid token - reject submission
        return BadRequest($"Verification failed: {string.Join(", ", validation.ErrorCodes)}");
    }
}
```

---

## Advanced validation techniques

**Idempotency keys for retry operation**

```js
const crypto = require("crypto");


async function validateWithRetry(token, remoteip, maxRetries = 3) {
  const idempotencyKey = crypto.randomUUID();


  for (let attempt = 1; attempt <= maxRetries; attempt++) {
    try {
      const formData = new FormData();
      formData.append("secret", SECRET_KEY);
      formData.append("response", token);
      formData.append("remoteip", remoteip);
      formData.append("idempotency_key", idempotencyKey);


      const response = await fetch(
        "https://challenges.cloudflare.com/turnstile/v0/siteverify",
        {
          method: "POST",
          body: formData,
        },
      );


      const result = await response.json();


      if (response.ok) {
        return result;
      }


      // If this is the last attempt, return the error
      if (attempt === maxRetries) {
        return result;
      }


      // Wait before retrying (exponential backoff)
      await new Promise((resolve) =>
        setTimeout(resolve, Math.pow(2, attempt) * 1000),
      );
    } catch (error) {
      if (attempt === maxRetries) {
        return { success: false, "error-codes": ["internal-error"] };
      }
    }
  }
}
```

**Enhanced validation with custom checks**

```js
async function validateTurnstileEnhanced(
  token,
  remoteip,
  expectedAction = null,
  expectedHostname = null,
) {
  const validation = await validateTurnstile(token, remoteip);


  if (!validation.success) {
    return {
      valid: false,
      reason: "turnstile_failed",
      errors: validation["error-codes"],
    };
  }


  // Check if action matches expected value (if specified)
  if (expectedAction && validation.action !== expectedAction) {
    return {
      valid: false,
      reason: "action_mismatch",
      expected: expectedAction,
      received: validation.action,
    };
  }


  // Check if hostname matches expected value (if specified)
  if (expectedHostname && validation.hostname !== expectedHostname) {
    return {
      valid: false,
      reason: "hostname_mismatch",
      expected: expectedHostname,
      received: validation.hostname,
    };
  }


  // Check token age (warn if older than 4 minutes)
  const challengeTime = new Date(validation.challenge_ts);
  const now = new Date();
  const ageMinutes = (now - challengeTime) / (1000 * 60);


  if (ageMinutes > 4) {
    console.warn(`Token is ${ageMinutes.toFixed(1)} minutes old`);
  }


  return {
    valid: true,
    data: validation,
    tokenAge: ageMinutes,
  };
}


// Usage
const result = await validateTurnstileEnhanced(
  token,
  remoteip,
  "login", // expected action
  "example.com", // expected hostname
);


if (result.valid) {
  // Process the request
  console.log("Validation successful:", result.data);
} else {
  // Handle validation failure
  console.log("Validation failed:", result.reason);
}
```

---

## API response format

* [ Successful response ](#tab-panel-11836)
* [ Failed response ](#tab-panel-11837)

**Example**

```json
{
  "success": true,
  "challenge_ts": "2022-02-28T15:14:30.096Z",
  "hostname": "example.com",
  "error-codes": [],
  "action": "login",
  "cdata": "sessionid-123456789",
  "metadata": {
    "ephemeral_id": "x:9f78e0ed210960d7693b167e"
  }
}
```

**Example**

```json
{
  "success": false,
  "error-codes": ["invalid-input-response"]
}
```

### Response fields

| Field                  | Description                                      |
| ---------------------- | ------------------------------------------------ |
| success                | Boolean indicating if validation was successful  |
| challenge\_ts          | ISO 8601 timestamp when the challenge was solved |
| hostname               | Hostname where the challenge was served          |
| error-codes            | Array of error codes (if validation failed)      |
| action                 | Custom action identifier from client-side        |
| cdata                  | Custom data payload from client-side             |
| metadata.ephemeral\_id | Device fingerprint ID (Enterprise only)          |

### Error codes reference

| Error code             | Description                             | Action required                                   |
| ---------------------- | --------------------------------------- | ------------------------------------------------- |
| missing-input-secret   | Secret parameter not provided           | Ensure secret key is included                     |
| invalid-input-secret   | Secret key is invalid or expired        | Check your secret key in the Cloudflare dashboard |
| missing-input-response | Response parameter was not provided     | Ensure token is included                          |
| invalid-input-response | Token is invalid, malformed, or expired | User should retry the challenge                   |
| bad-request            | Request is malformed                    | Check request format and parameters               |
| timeout-or-duplicate   | Token has already been validated        | Each token can only be used once                  |
| internal-error         | Internal error occurred                 | Retry the request                                 |

---

## Implementation

**Example implementation**

```js
class TurnstileValidator {
  constructor(secretKey, timeout = 10000) {
    this.secretKey = secretKey;
    this.timeout = timeout;
  }


  async validate(token, remoteip, options = {}) {
    // Input validation
    if (!token || typeof token !== "string") {
      return { success: false, error: "Invalid token format" };
    }


    if (token.length > 2048) {
      return { success: false, error: "Token too long" };
    }


    // Prepare request
    const controller = new AbortController();
    const timeoutId = setTimeout(() => controller.abort(), this.timeout);


    try {
      const formData = new FormData();
      formData.append("secret", this.secretKey);
      formData.append("response", token);


      if (remoteip) {
        formData.append("remoteip", remoteip);
      }


      if (options.idempotencyKey) {
        formData.append("idempotency_key", options.idempotencyKey);
      }


      const response = await fetch(
        "https://challenges.cloudflare.com/turnstile/v0/siteverify",
        {
          method: "POST",
          body: formData,
          signal: controller.signal,
        },
      );


      const result = await response.json();


      // Additional validation
      if (result.success) {
        if (
          options.expectedAction &&
          result.action !== options.expectedAction
        ) {
          return {
            success: false,
            error: "Action mismatch",
            expected: options.expectedAction,
            received: result.action,
          };
        }


        if (
          options.expectedHostname &&
          result.hostname !== options.expectedHostname
        ) {
          return {
            success: false,
            error: "Hostname mismatch",
            expected: options.expectedHostname,
            received: result.hostname,
          };
        }
      }


      return result;
    } catch (error) {
      if (error.name === "AbortError") {
        return { success: false, error: "Validation timeout" };
      }


      console.error("Turnstile validation error:", error);
      return { success: false, error: "Internal error" };
    } finally {
      clearTimeout(timeoutId);
    }
  }
}


// Usage
const validator = new TurnstileValidator(process.env.TURNSTILE_SECRET_KEY);


const result = await validator.validate(token, remoteip, {
  expectedAction: "login",
  expectedHostname: "example.com",
});


if (result.success) {
  // Process the request
} else {
  // Handle failure
  console.log("Validation failed:", result.error);
}
```

---

## Testing

You can test the dummy token generated with testing sitekey via Siteverify API with the testing secret key. Your production secret keys will reject dummy tokens.

Refer to [Testing](https://edgetunnel-b2h.pages.dev/turnstile/troubleshooting/testing/) for more information.

---

## Best practices

### Security

* Store your secret keys securely. Use environment variables or secure key management.
* Validate the token on every request. Never trust client-side validation alone.
* Check additional fields. Validate the action and hostname when specified.
* Monitor for abuse and log failed validations and unusual patterns.
* Use HTTPS. Always validate over secure connections.
* Only call the Siteverify API in your backend environment. If you expose the secret key in the front-end client code to call Siteverify, attackers can bypass the security check. Ensure that your client-side code sends the validation token to your backend, and that your backend is the sole caller of the Siteverify API.

### Performance

* Set reasonable timeouts. Do not wait indefinitely for Siteverify responses.
* Implement retry logic and handle temporary network issues.
* Cache validation results for the same token, if it is needed for your flow.
* Monitor your API latency. Track the Siteverify response time.

### Error handling

* Have fallback behavior for API failures.
* Use user-friendly messaging. Do not expose internal error details to users.
* Properly log errors for debugging without exposing secrets.
* Rate limit to protect against validation flooding.

```json
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```