Anthropic

Anthropic ↗︎ helps build reliable, interpretable, and steerable AI systems.

Endpoint

Base URL

https://gateway.ai.cloudflare.com/v1/{account_id}/{gateway_id}/anthropic

When supplying a provider key to /anthropic/v1/messages, send it in x-api-key. AI Gateway does not recognize Authorization: Bearer as provider credentials on this endpoint. Authenticate to AI Gateway separately with cf-aig-authorization.

For stored keys and Unified Billing, refer to credential precedence. If provider credentials are required but AI Gateway cannot find them, refer to error 2044.

Examples

cURL

With API Key in Request

curl https://gateway.ai.cloudflare.com/v1/{account_id}/{gateway_id}/anthropic/v1/messages \
 --header 'x-api-key: {anthropic_api_key}' \
 --header 'cf-aig-authorization: Bearer {CF_AIG_TOKEN}' \
 --header 'anthropic-version: 2023-06-01' \
 --header 'Content-Type: application/json' \
 --data  '{
    "model": "claude-sonnet-4-5",
    "max_tokens": 1024,
    "messages": [
      {"role": "user", "content": "What is Cloudflare?"}
    ]
  }'

curl https://gateway.ai.cloudflare.com/v1/{account_id}/{gateway_id}/anthropic/v1/messages \
 --header 'x-api-key: {anthropic_api_key}' \
 --header 'anthropic-version: 2023-06-01' \
 --header 'Content-Type: application/json' \
 --data  '{
    "model": "claude-sonnet-4-5",
    "max_tokens": 1024,
    "messages": [
      {"role": "user", "content": "What is Cloudflare?"}
    ]
  }'

With Stored Keys (BYOK) / Unified Billing

curl https://gateway.ai.cloudflare.com/v1/{account_id}/{gateway_id}/anthropic/v1/messages \
 --header 'cf-aig-authorization: Bearer {CF_AIG_TOKEN}' \
 --header 'anthropic-version: 2023-06-01' \
 --header 'Content-Type: application/json' \
 --data  '{
    "model": "claude-sonnet-4-5",
    "max_tokens": 1024,
    "messages": [
      {"role": "user", "content": "What is Cloudflare?"}
    ]
  }'

Anthropic SDK

Set x-api-key explicitly when supplying your Anthropic key. SDK authentication headers can differ between versions. Setting Authorization to null removes the SDK-generated bearer header. Use cf-aig-authorization separately to authenticate to AI Gateway.

With Key in Request

import Anthropic from "@anthropic-ai/sdk";

const baseURL = `https://gateway.ai.cloudflare.com/v1/{accountId}/{gatewayId}/anthropic`;
const providerKey = "{ANTHROPIC_API_KEY}";

const anthropic = new Anthropic({
	apiKey: providerKey,
	baseURL,
	defaultHeaders: {
		"x-api-key": providerKey,
		"cf-aig-authorization": "Bearer {CF_AIG_TOKEN}",
		Authorization: null,
	},
});

const message = await anthropic.messages.create({
	model: "claude-sonnet-4-5",
	messages: [{ role: "user", content: "What is Cloudflare?" }],
	max_tokens: 1024,
});

import Anthropic from "@anthropic-ai/sdk";

const baseURL = `https://gateway.ai.cloudflare.com/v1/{accountId}/{gatewayId}/anthropic`;
const providerKey = "{ANTHROPIC_API_KEY}";

const anthropic = new Anthropic({
	apiKey: providerKey,
	baseURL,
	defaultHeaders: {
		"x-api-key": providerKey,
		Authorization: null,
	},
});

const message = await anthropic.messages.create({
	model: "claude-sonnet-4-5",
	messages: [{ role: "user", content: "What is Cloudflare?" }],
	max_tokens: 1024,
});

With Stored Keys (BYOK) / Unified Billing

import Anthropic from "@anthropic-ai/sdk";

const baseURL = `https://gateway.ai.cloudflare.com/v1/{accountId}/{gatewayId}/anthropic`;

const anthropic = new Anthropic({
	apiKey: "placeholder",
	baseURL,
	defaultHeaders: {
		"cf-aig-authorization": "Bearer {CF_AIG_TOKEN}",
		"x-api-key": null,
		Authorization: null,
	},
});

const message = await anthropic.messages.create({
	model: "claude-sonnet-4-5",
	messages: [{ role: "user", content: "What is Cloudflare?" }],
	max_tokens: 1024,
});

OpenAI-Compatible Endpoint

You can also access Anthropic models using the OpenAI API schema through the REST API. Send your requests to:

https://api.cloudflare.com/client/v4/accounts/{account_id}/ai/v1/chat/completions

Specify:


{
	"model": "anthropic/{model}"
}