Anthropic

In this guide, you will connect AISIX AI Gateway to Anthropic. Callers reach Claude models through the gateway's OpenAI-compatible API or the native Anthropic Messages API. AISIX owns the credential, model allowlist, rate limits, and usage accounting.

Anthropic is a native upstream: it uses the anthropic adapter and its own x-api-key authentication. Use this configuration to call Claude directly on api.anthropic.com. To reach Claude through AWS, use the AWS Bedrock Upstream instead.

Prerequisites

Before starting, prepare the following:

A gateway with the admin API on :3001 and the proxy API on :3000.
The admin key from the gateway config.yaml.
An Anthropic API key from the Anthropic Console and the Claude model ID you want to expose, for example claude-sonnet-5.

Supported Capabilities

Anthropic is the native backend for the Messages API, and it also serves chat completions through translation.

Endpoint	Supported	Streaming	Notes
`/v1/messages`	Yes	Yes	Native Anthropic Messages API.
`/v1/messages/count_tokens`	Yes	—	Anthropic-backed token counting.
`/v1/chat/completions`	Yes	Yes	OpenAI-shaped requests translated to Messages. Non-text content blocks are dropped in translation.
`/v1/embeddings`	No	—	Embeddings require the `openai` adapter.
`/v1/images/generations`	No	—	Rejected: image generation requires `provider: "openai"`.
`/v1/rerank`	No	—	Anthropic is not in the rerank allowlist (`openai`, `cohere`, `jina`).

See Provider Compatibility for the exact per-endpoint rules.

Configure the Anthropic Upstream

Create a provider key, model alias, and caller API key for the Anthropic-backed route.

Create a Provider Key

export AISIX_ADMIN_KEY="YOUR_ADMIN_KEY"
export ANTHROPIC_API_KEY="YOUR_PROVIDER_API_KEY"

curl -sS -X POST "http://127.0.0.1:3001/admin/v1/provider_keys" \
  -H "Authorization: Bearer ${AISIX_ADMIN_KEY}" \
  -H "Content-Type: application/json" \
  -d '{
    "display_name": "anthropic-prod",
    "provider": "anthropic",
    "adapter": "anthropic",
    "secret": "'"${ANTHROPIC_API_KEY}"'"
  }'

❶ provider is anthropic.

❷ adapter is anthropic. AISIX sends the credential as the x-api-key header and adds anthropic-version: 2023-06-01 on outbound calls.

❸ secret stores the Anthropic API key. It follows the credential-handling behavior in Provider Credentials.

You can omit api_base for Anthropic; it defaults to https://api.anthropic.com. Copy the returned provider key ID.

Create a Model

export PROVIDER_KEY_ID="YOUR_PROVIDER_KEY_ID"

curl -sS -X POST "http://127.0.0.1:3001/admin/v1/models" \
  -H "Authorization: Bearer ${AISIX_ADMIN_KEY}" \
  -H "Content-Type: application/json" \
  -d '{
    "display_name": "claude-sonnet-prod",
    "provider": "anthropic",
    "model_name": "claude-sonnet-5",
    "provider_key_id": "'"${PROVIDER_KEY_ID}"'"
  }'

❶ display_name is the alias callers send in model.

❷ model_name is the Claude model ID, for example claude-sonnet-5, claude-opus-4-8, or claude-haiku-4-5.

❸ provider_key_id attaches the alias to the Anthropic provider key.

Create a Caller API Key

Choose the caller API key value that the application will send to AISIX, then hash it for the admin resource:

export AISIX_API_KEY="YOUR_CALLER_API_KEY"

CALLER_KEY_HASH=$(printf '%s' "${AISIX_API_KEY}" | shasum -a 256 | awk '{print $1}')

curl -sS -X POST "http://127.0.0.1:3001/admin/v1/apikeys" \
  -H "Authorization: Bearer ${AISIX_ADMIN_KEY}" \
  -H "Content-Type: application/json" \
  -d '{
    "key_hash": "'"${CALLER_KEY_HASH}"'",
    "allowed_models": ["claude-sonnet-prod"]
  }'

❶ allowed_models must match the model alias you created.

Verify the Upstream

Send a native Messages request through the AISIX proxy:

curl -sS -X POST "http://127.0.0.1:3000/v1/messages" \
  -H "Authorization: Bearer ${AISIX_API_KEY}" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-prod",
    "max_tokens": 64,
    "messages": [{"role": "user", "content": "Say hello from Claude."}]
  }'

The gateway returns an Anthropic Messages response that echoes the caller-facing alias claude-sonnet-prod. The same alias also works on /v1/chat/completions for OpenAI-shaped clients. If AISIX returns an upstream authentication error, check the provider key secret.

Behavior and Limits

Callers authenticate to AISIX with a caller API key in the Authorization: Bearer header. AISIX supplies the Anthropic x-api-key and anthropic-version headers to the upstream; clients do not send them.

On /v1/chat/completions, OpenAI-shaped requests are translated to the Messages API, and non-text content blocks such as images are dropped during translation. For image or document inputs, call /v1/messages directly. See Anthropic Messages.

Claude model IDs from the 4.6 generation onward are pinned snapshots, not evergreen pointers. Check the Anthropic models reference for the current IDs.

Next Steps

Anthropic SDK Quickstart — call this alias from an Anthropic SDK at /v1/messages.
Anthropic Messages — the native Messages request and response shape.
Provider Compatibility — the endpoint-by-endpoint support rules.

Prerequisites​

Supported Capabilities​

Configure the Anthropic Upstream​

Create a Provider Key​

Create a Model​

Create a Caller API Key​

Verify the Upstream​

Behavior and Limits​

Next Steps​