Claude API PHP Example

Working PHP code for calling the Claude API using cURL and Guzzle. No official PHP SDK needed — these copy-paste examples work with Laravel, WordPress, and plain PHP scripts.

PHP has no official Anthropic SDK, so the standard approach is to call the REST API via cURL or Guzzle. These examples work in plain PHP 8+, Laravel, Symfony, and WordPress.

Minimal cURL example

<?php
function claude(string $prompt, string $model = "claude-sonnet-4-6", int $maxTokens = 1024): string {
    $ch = curl_init("https://api.anthropic.com/v1/messages");
    curl_setopt_array($ch, [
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_POST           => true,
        CURLOPT_HTTPHEADER     => [
            "x-api-key: " . getenv("ANTHROPIC_API_KEY"),
            "anthropic-version: 2023-06-01",
            "content-type: application/json",
        ],
        CURLOPT_POSTFIELDS => json_encode([
            "model"      => $model,
            "max_tokens" => $maxTokens,
            "messages"   => [["role" => "user", "content" => $prompt]],
        ]),
    ]);
    $response = curl_exec($ch);
    curl_close($ch);
    return json_decode($response, true)["content"][0]["text"];
}

echo claude("Explain PHP 8 fibers in one paragraph.");

With system prompt

$body = json_encode([
    "model"      => "claude-sonnet-4-6",
    "max_tokens" => 512,
    "system"     => "You are a concise PHP expert. Respond in bullet points.",
    "messages"   => [["role" => "user", "content" => "What is the difference between abstract classes and interfaces in PHP?"]],
]);

Reusable ClaudeClient class

<?php
class ClaudeClient {
    private string $apiKey;
    private string $model;
    const BASE_URL = "https://api.anthropic.com/v1/messages";

    public function __construct(string $apiKey = "", string $model = "claude-sonnet-4-6") {
        $this->apiKey = $apiKey ?: getenv("ANTHROPIC_API_KEY");
        $this->model  = $model;
    }

    public function chat(array $messages, ?string $system = null, int $maxTokens = 1024): string {
        $body = ["model" => $this->model, "max_tokens" => $maxTokens, "messages" => $messages];
        if ($system) $body["system"] = $system;

        $ch = curl_init(self::BASE_URL);
        curl_setopt_array($ch, [
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_POST           => true,
            CURLOPT_HTTPHEADER     => $this->headers(),
            CURLOPT_POSTFIELDS     => json_encode($body),
        ]);

        $res  = curl_exec($ch);
        $code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        curl_close($ch);

        if ($code !== 200) throw new RuntimeException("Claude API error $code: $res");
        return json_decode($res, true)["content"][0]["text"];
    }

    private function headers(): array {
        return [
            "x-api-key: " . $this->apiKey,
            "anthropic-version: 2023-06-01",
            "content-type: application/json",
        ];
    }
}

$client = new ClaudeClient();
echo $client->chat([["role" => "user", "content" => "Write a PHP function to sanitize user input."]]);

Streaming response

<?php
header("Content-Type: text/event-stream");
header("Cache-Control: no-cache");

$body = json_encode([
    "model"      => "claude-sonnet-4-6",
    "max_tokens" => 1024,
    "stream"     => true,
    "messages"   => [["role" => "user", "content" => "Write a tutorial on PHP 8 match expressions."]],
]);

$buffer = "";
$ch = curl_init("https://api.anthropic.com/v1/messages");
curl_setopt_array($ch, [
    CURLOPT_POST       => true,
    CURLOPT_HTTPHEADER => [
        "x-api-key: " . getenv("ANTHROPIC_API_KEY"),
        "anthropic-version: 2023-06-01",
        "content-type: application/json",
    ],
    CURLOPT_POSTFIELDS    => $body,
    CURLOPT_WRITEFUNCTION => function ($ch, $chunk) use (&$buffer) {
        $buffer .= $chunk;
        while (($pos = strpos($buffer, "
")) !== false) {
            $line   = substr($buffer, 0, $pos);
            $buffer = substr($buffer, $pos + 1);
            if (!str_starts_with($line, "data: ")) continue;
            $data = json_decode(substr($line, 6), true);
            if ($data["type"] ?? "" === "content_block_delta") {
                echo "data: " . json_encode(["text" => $data["delta"]["text"]]) . "

";
                ob_flush(); flush();
            }
        }
        return strlen($chunk);
    },
]);
curl_exec($ch);
curl_close($ch);

Guzzle example (Laravel / Composer projects)

// composer require guzzlehttp/guzzle
use GuzzleHttpClient;

$http = new Client(["base_uri" => "https://api.anthropic.com"]);
$res  = $http->post("/v1/messages", [
    "headers" => [
        "x-api-key"         => env("ANTHROPIC_API_KEY"),
        "anthropic-version" => "2023-06-01",
    ],
    "json" => [
        "model"      => "claude-sonnet-4-6",
        "max_tokens" => 1024,
        "messages"   => [["role" => "user", "content" => "Explain Laravel service containers."]],
    ],
]);
$reply = json_decode($res->getBody(), true)["content"][0]["text"];

WordPress integration

// wp-config.php
define('ANTHROPIC_API_KEY', 'sk-ant-...');

// functions.php or plugin
function claude_wp(string $prompt): string {
    $response = wp_remote_post("https://api.anthropic.com/v1/messages", [
        "headers" => [
            "x-api-key"         => ANTHROPIC_API_KEY,
            "anthropic-version" => "2023-06-01",
            "content-type"      => "application/json",
        ],
        "body"    => json_encode([
            "model"      => "claude-sonnet-4-6",
            "max_tokens" => 512,
            "messages"   => [["role" => "user", "content" => $prompt]],
        ]),
        "timeout" => 30,
    ]);
    return json_decode(wp_remote_retrieve_body($response), true)["content"][0]["text"];
}

cURL vs Guzzle — when to use each

To estimate costs for your PHP application, use the Claude API Cost Calculator. For model pricing details, see the Anthropic API pricing guide.

Frequently asked questions

Free tools

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