Anthropic

Last updated Oct 27, 2026 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

<details>

<summary>

With API Key in Request

</summary>

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?"}
    ]
  }'

</details>

<details>

<summary>

With Stored Keys (BYOK) / Unified Billing

</summary>

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?"}
    ]
  }'

</details>

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.

<details>

<summary>

With Key in Request

</summary>

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,
});

</details>

<details>

<summary>

With Stored Keys (BYOK) / Unified Billing

</summary>

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,
});

Note

The placeholder satisfies the SDK's credential configuration. The <code>null</code> headers remove SDK-generated provider credentials before sending the request. AI Gateway uses an applicable stored BYOK key, or falls back to Unified Billing when allowed. If Require provider credentials is on and no applicable stored key exists, the request returns <a href="https://developers.cloudflare.com/ai-gateway/reference/troubleshooting/#400-provider-credentials-required-2044">error <code>2044</code></a>.

Supplying a real key in <code>x-api-key</code> instead selects request-key authentication. This bypasses stored keys and Unified Billing.

</details>

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}"
}

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Anthropic - 图1Docs

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description: Route Azure OpenAI requests through AI Gateway for observability and control. title: Azure OpenAI image: https://developers.cloudflare.com/ai-gateway/usage/providers/azureopenai/og.png?v=8e2c7a0520ad1a06

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