Anthropic PHP API library

The Anthropic PHP library provides convenient access to the Anthropic REST API from any PHP 8.1.0+ application.

Documentation

The REST API documentation can be found on docs.anthropic.com.

Installation

composer require "anthropic-ai/sdk 0.5.0"

Usage

This library uses named parameters to specify optional arguments. Parameters with a default value must be set by name.

<?php

use Anthropic\Client;

$client = new Client(
  apiKey: getenv('ANTHROPIC_API_KEY') ?: 'my-anthropic-api-key'
);

$message = $client->messages->create(
  maxTokens: 1024,
  messages: [['role' => 'user', 'content' => 'Hello, Claude']],
  model: 'claude-sonnet-4-5-20250929',
);

var_dump($message->content);

Value Objects

It is recommended to use the static with constructor Base64ImageSource::with(data: 'U3RhaW5sZXNzIHJvY2tz', ...) and named parameters to initialize value objects.

However, builders are also provided (new Base64ImageSource)->withData('U3RhaW5sZXNzIHJvY2tz').

Streaming

We provide support for streaming responses using Server-Sent Events (SSE).

<?php

use Anthropic\Client;

$client = new Client(
  apiKey: getenv('ANTHROPIC_API_KEY') ?: 'my-anthropic-api-key'
);

$stream = $client->messages->createStream(
  maxTokens: 1024,
  messages: [['role' => 'user', 'content' => 'Hello, Claude']],
  model: 'claude-sonnet-4-5-20250929',
);

foreach ($stream as $message) {
  var_dump($message);
}

Pagination

List methods in the Anthropic API are paginated.

This library provides auto-paginating iterators with each list response, so you do not have to request successive pages manually:

<?php

use Anthropic\Client;

$client = new Client(
  apiKey: getenv('ANTHROPIC_API_KEY') ?: 'my-anthropic-api-key'
);

$page = $client->beta->messages->batches->list(limit: 20);

var_dump($page);

// fetch items from the current page
foreach ($page->getItems() as $item) {
  var_dump($item->id);
}
// make additional network requests to fetch items from all pages, including and after the current page
foreach ($page->pagingEachItem() as $item) {
  var_dump($item->id);
}

Handling errors

When the library is unable to connect to the API, or if the API returns a non-success status code (i.e., 4xx or 5xx response), a subclass of Anthropic\Core\Exceptions\APIException will be thrown:

<?php

use Anthropic\Core\Exceptions\APIConnectionException;
use Anthropic\Core\Exceptions\RateLimitException;
use Anthropic\Core\Exceptions\APIStatusException;

try {
  $message = $client->messages->create(
    maxTokens: 1024,
    messages: [['role' => 'user', 'content' => 'Hello, Claude']],
    model: 'claude-sonnet-4-5-20250929',
  );
} catch (APIConnectionException $e) {
  echo "The server could not be reached", PHP_EOL;
  var_dump($e->getPrevious());
} catch (RateLimitException $e) {
  echo "A 429 status code was received; we should back off a bit.", PHP_EOL;
} catch (APIStatusException $e) {
  echo "Another non-200-range status code was received", PHP_EOL;
  echo $e->getMessage();
}

Error codes are as follows:

Cause	Error Type
HTTP 400	BadRequestException
HTTP 401	AuthenticationException
HTTP 403	PermissionDeniedException
HTTP 404	NotFoundException
HTTP 409	ConflictException
HTTP 422	UnprocessableEntityException
HTTP 429	RateLimitException
HTTP >= 500	InternalServerException
Other HTTP error	APIStatusException
Timeout	APITimeoutException
Network error	APIConnectionException

Retries

Certain errors will be automatically retried 2 times by default, with a short exponential backoff.

Connection errors (for example, due to a network connectivity problem), 408 Request Timeout, 409 Conflict, 429 Rate Limit, >=500 Internal errors, and timeouts will all be retried by default.

You can use the maxRetries option to configure or disable this:

<?php

use Anthropic\Client;

// Configure the default for all requests:
$client = new Client(requestOptions: ['maxRetries' => 0]);

// Or, configure per-request:
$result = $client->messages->create(
  maxTokens: 1024,
  messages: [['role' => 'user', 'content' => 'Hello, Claude']],
  model: 'claude-sonnet-4-5-20250929',
  requestOptions: ['maxRetries' => 5],
);

Advanced concepts

Making custom or undocumented requests

Undocumented properties

You can send undocumented parameters to any endpoint, and read undocumented response properties, like so:

Note: the extra* parameters of the same name overrides the documented parameters.

<?php

$message = $client->messages->create(
  maxTokens: 1024,
  messages: [['role' => 'user', 'content' => 'Hello, Claude']],
  model: 'claude-sonnet-4-5-20250929',
  requestOptions: [
    'extraQueryParams' => ['my_query_parameter' => 'value'],
    'extraBodyParams' => ['my_body_parameter' => 'value'],
    'extraHeaders' => ['my-header' => 'value'],
  ],
);

Undocumented request params

If you want to explicitly send an extra param, you can do so with the extra_query, extra_body, and extra_headers under the request_options: parameter when making a request, as seen in the examples above.

Undocumented endpoints

To make requests to undocumented endpoints while retaining the benefit of auth, retries, and so on, you can make requests using client.request, like so:

<?php

$response = $client->request(
  method: "post",
  path: '/undocumented/endpoint',
  query: ['dog' => 'woof'],
  headers: ['useful-header' => 'interesting-value'],
  body: ['hello' => 'world']
);

Versioning

This package follows SemVer conventions. As the library is in initial development and has a major version of 0, APIs may change at any time.

This package considers improvements to the (non-runtime) PHPDoc type definitions to be non-breaking changes.

Requirements

PHP 8.1.0 or higher.

Contributing

See the contributing documentation.