---
title: PHP Server SDK
---

# PHP Server SDK

Official PHP server-side SDK — published as [`captchala/captchala-php`](https://packagist.org/packages/captchala/captchala-php) on Packagist.

Three jobs the SDK handles for you:

1. **Validate** — verify a `pt_` pass token from the browser SDK.
2. **Issue** — mint a one-time `sct_` server token to bind the upcoming challenge to a specific action / IP / UID.
3. **Moderate** — multi-modal (text + image) content moderation against the same OpenAI-compatible pipeline the dashboard uses.

## Install

```bash
composer require captchala/captchala-php
```

Requires **PHP ≥ 8.0** with `ext-json`. Uses cURL when available, falls back to `file_get_contents`.

## Validate (`pt_` token)

Pass the end-user's IP as the third argument (from `CF-Connecting-IP` /
`X-Forwarded-For`, falling back to `REMOTE_ADDR`). Optional, but
**recommended** — it's used for additional risk checks.

```php
use Captchala\Client;

$client = new Client('your_app_key', 'your_app_secret');
$result = $client->validate($_POST['captcha_token'], false, captchala_client_ip());

if (!$result->isValid()) {
    http_response_code(400);
    exit($result->getError());   // e.g. "token_expired"
}
// Verification passed; proceed with the request.
// $result->getCaptchaArgs() has platform / user_ip / referer / pkg / solved_at / risk_score

// Real end-user IP behind a CDN / proxy
function captchala_client_ip(): string {
    foreach (['HTTP_CF_CONNECTING_IP', 'HTTP_X_FORWARDED_FOR', 'HTTP_X_REAL_IP', 'REMOTE_ADDR'] as $h) {
        if (!empty($_SERVER[$h])) {
            $ip = trim(explode(',', $_SERVER[$h])[0]);
            if (filter_var($ip, FILTER_VALIDATE_IP)) return $ip;
        }
    }
    return '';
}
```

No IP handy? Use `$client->validate($_POST['captcha_token'])` — it still
verifies, just without the extra IP-based risk signal.

If you issued the original `server_token` with `bind_uid`, compare the `uid` returned with the user you actually expect:

```php
if ($result->getUid() !== $expectedUserId) {
    http_response_code(400);
    exit('user mismatch');
}
```

## Issue a server token

For high-value flows (login, register, payment) the recommended pattern is:
backend mints a one-time `sct_` token, hands it to the browser, browser passes
it as the `serverToken` prop. Each token is single-use, action-scoped, and
optionally bound to IP / UID at issuance time.

```php
$issue = $client->issueServerToken(
    action:    'login',
    bindingIp: $request->ip(),
    ttl:       300,         // seconds; default 300
    maxUses:   5,           // SDK retry budget
    bindUid:   $user->id,   // pair with ValidateResult::getUid() on verify
);

if (!$issue->isOk()) {
    return ['error' => $issue->getError()];   // rate_limit_exceeded, invalid_action, ...
}

return ['server_token' => $issue->getToken()];  // hand to browser
```

## Moderate content

Multi-modal — accepts a mix of text and image URLs in OpenAI-compatible format:

```php
$result = $client->moderationCheck([
    ['type' => 'text', 'text' => $userComment],
    ['type' => 'image_url', 'image_url' => ['url' => $uploadedImageUrl]],
], userId: $user->id);

if (!$result->isOk()) {
    // request error: invalid_credentials, no_content, transport failure, ...
    return ['error' => $result->getError()];
}

if ($result->isFlagged()) {
    // upstream model flagged; inspect categories for the why
    if ($result->hasCategory('violence', 'csam')) {
        // hard block
    }
}
```

Plain-text shortcut:

```php
$result = $client->moderationText('user comment here', userId: $user->id);
```

Categories are model-defined (e.g. `violence`, `hate`, `sexual`, `self-harm`); iterate `getCategories()` defensively rather than hard-coding a fixed set.

## Result classes

| Class | Methods |
|---|---|
| `ValidateResult` | `isValid()`, `getError()`, `getUid()`, `getChallengeId()`, `getAction()`, `isOffline()`, `isClientOnly()`, `getWarning()`, `toArray()` |
| `IssueResult` | `isOk()`, `getToken()`, `getExpiresIn()`, `getIssuedAt()`, `getError()`, `getMessage()`, `toArray()` |
| `ModerationResult` | `isOk()`, `isFlagged()`, `hasCategory(...$names)`, `getCategories()`, `getContentType()`, `getRaw()`, `getError()`, `getMessage()`, `toArray()` |

## Links

- [Packagist](https://packagist.org/packages/captchala/captchala-php) · [GitHub](https://github.com/Captcha-La/captchala-php)
- [Web SDK overview](/web-sdk) · [API Reference](/api-reference)