curl --request POST \
  --url https://api.anthropic.com/v1/messages \
  --header 'Content-Type: application/json' \
  --header 'anthropic-version: <anthropic-version>' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "model": "claude-sonnet-4-6",
  "max_tokens": 1024,
  "messages": [
    {
      "role": "user",
      "content": "Hello, Claude. Respond in one sentence."
    }
  ]
}
'

import requests

url = "https://api.anthropic.com/v1/messages"

payload = {
    "model": "claude-sonnet-4-6",
    "max_tokens": 1024,
    "messages": [
        {
            "role": "user",
            "content": "Hello, Claude. Respond in one sentence."
        }
    ]
}
headers = {
    "anthropic-version": "<anthropic-version>",
    "x-api-key": "<api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {
    'anthropic-version': '<anthropic-version>',
    'x-api-key': '<api-key>',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    model: 'claude-sonnet-4-6',
    max_tokens: 1024,
    messages: [{role: 'user', content: 'Hello, Claude. Respond in one sentence.'}]
  })
};

fetch('https://api.anthropic.com/v1/messages', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.anthropic.com/v1/messages",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'model' => 'claude-sonnet-4-6',
    'max_tokens' => 1024,
    'messages' => [
        [
                'role' => 'user',
                'content' => 'Hello, Claude. Respond in one sentence.'
        ]
    ]
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "anthropic-version: <anthropic-version>",
    "x-api-key: <api-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

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

func main() {

	url := "https://api.anthropic.com/v1/messages"

	payload := strings.NewReader("{\n  \"model\": \"claude-sonnet-4-6\",\n  \"max_tokens\": 1024,\n  \"messages\": [\n    {\n      \"role\": \"user\",\n      \"content\": \"Hello, Claude. Respond in one sentence.\"\n    }\n  ]\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("anthropic-version", "<anthropic-version>")
	req.Header.Add("x-api-key", "<api-key>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.anthropic.com/v1/messages")
  .header("anthropic-version", "<anthropic-version>")
  .header("x-api-key", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"model\": \"claude-sonnet-4-6\",\n  \"max_tokens\": 1024,\n  \"messages\": [\n    {\n      \"role\": \"user\",\n      \"content\": \"Hello, Claude. Respond in one sentence.\"\n    }\n  ]\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.anthropic.com/v1/messages")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["anthropic-version"] = '<anthropic-version>'
request["x-api-key"] = '<api-key>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"model\": \"claude-sonnet-4-6\",\n  \"max_tokens\": 1024,\n  \"messages\": [\n    {\n      \"role\": \"user\",\n      \"content\": \"Hello, Claude. Respond in one sentence.\"\n    }\n  ]\n}"

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

{
  "id": "msg_01XFDUDYJgAACzvnptvVoYEL",
  "type": "message",
  "role": "assistant",
  "content": [
    {
      "type": "text",
      "text": "Hello! How can I help you today?"
    }
  ],
  "model": "claude-sonnet-4-6",
  "stop_reason": "end_turn",
  "stop_details": {},
  "usage": {
    "input_tokens": 17,
    "output_tokens": 12,
    "cache_creation_input_tokens": 0,
    "cache_read_input_tokens": 0,
    "service_tier": "standard",
    "inference_geo": "global"
  }
}

{
  "type": "error",
  "error": {
    "type": "authentication_error",
    "message": "invalid x-api-key"
  },
  "request_id": "req_011CdDNcA4MfikfhDdfNYDNj"
}

{
  "type": "error",
  "error": {
    "type": "authentication_error",
    "message": "invalid x-api-key"
  },
  "request_id": "req_011CdDNcA4MfikfhDdfNYDNj"
}