Claude API Key: Console, Top-Up, Calls, and Proxies (2026)

The Claude API is the model interface provided by Anthropic, commonly used for long documents, code, agents, and complex reasoning. Many developers confuse three things on first setup: the Claude web subscription, Claude Code, and the Claude API.

This article explains how to obtain a Claude API Key, how to call the API, how to connect it to Claude Code, and the two common access options from mainland China.

Note: Claude and Anthropic are trademarks of their respective owners. This article reflects common usage as of October 2026. Endpoints and prices are subject to the official documentation and this site.

1. Separate the three concepts first

Name	What it is	How to use it
Claude web/App	Chat product	Buy a subscription
Claude Code	Command-line coding tool	Calls models through the API
Claude API	Model interface	Calls `/v1/messages` with a key

This article is about the Claude API Key. It is not a web membership account, and a web subscription cannot be used directly as an API key.

2. Route A: an official key from Anthropic Console

Open Anthropic Console.
Register or sign in.
Go to the API Keys page.
Create a key, name it, and save it.
Add a payment method and confirm your limits.
Copy the key and store it in a password manager.

The endpoint for an official key is usually:

https://api.anthropic.com

Requests require the x-api-key and anthropic-version headers. Follow the official documentation for details.

3. Route B: a key from ZSQH AI Gateway

If official endpoints are unstable from mainland China, or you need a unified bill and multiple models:

Open ZSQH AI Gateway and register.
Go to API Keys and create a key.
Set a spending limit and an expiry time.
Top up your wallet.
Copy the key.

The gateway offers two common modes:

Anthropic-compatible: for Claude Code and other tools that use the Anthropic protocol.
OpenAI-compatible: for the OpenAI SDK, Cursor, Chatbox, Dify, and similar tools, with the Base URL https://ai.zhongshangqihang.com/v1.

4. Calling the native Anthropic endpoint with curl

export ANTHROPIC_API_KEY="sk-your-key"

curl "https://ai.zhongshangqihang.com/v1/messages" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-4-5",
    "max_tokens": 256,
    "messages": [
      {"role": "user", "content": "Explain what an API gateway is in three sentences."}
    ]
  }'

Model names are listed under Model Pricing. If the gateway's Anthropic-compatible path differs, follow the provider's connection guide.

5. Calling Claude with the OpenAI SDK

Many tools only support the OpenAI protocol. In that case, use the gateway's OpenAI-compatible endpoint:

import os
from openai import OpenAI

client = OpenAI(
    api_key=os.environ["ANTHROPIC_API_KEY"],
    base_url="https://ai.zhongshangqihang.com/v1",
)

resp = client.chat.completions.create(
    model="claude-sonnet-4-5",
    messages=[{"role": "user", "content": "Reply with OK only"}],
)
print(resp.choices[0].message.content)

Note that the native Anthropic interface and the OpenAI-compatible interface use different request formats. Do not mix them.

6. Connecting to Claude Code

Claude Code uses the Anthropic protocol. A common configuration is:

export ANTHROPIC_BASE_URL="https://ai.zhongshangqihang.com"
export ANTHROPIC_API_KEY="sk-your-key"
claude

If your client requires ANTHROPIC_AUTH_TOKEN, replace it according to the client's documentation. For detailed steps, see the Claude Code API guide.

7. Common errors

Error	Cause	Fix
`401`	Wrong or expired key, or incorrect headers	Check `x-api-key` or Bearer authentication
`404`	Wrong Base URL or path	Use `/v1/messages` for native calls and `/v1` for OpenAI compatibility
`model not found`	Incorrect model name	Copy the name from the pricing page
`429`	Rate limit or quota	Lower concurrency, retry, or raise your limit
`insufficient quota`	Not enough balance	Top up
`anthropic-version` error	Missing version header	Add `anthropic-version: 2023-06-01`

8. Security recommendations

Do not expose keys in frontend code.
Use one key per person and set project-level limits.
Set expiry times and rotate keys regularly.
Never commit keys to Git.
Use environment variables or a secrets manager in production.

9. Direct official access vs a gateway

Dimension	Direct official access	ZSQH AI Gateway
Access	Depends on your network environment	Optimized for mainland China
Payment	Officially supported methods	Top-up on the provider's site
Models	Claude only	Claude, GPT, Gemini, DeepSeek, and more
Billing	Official dashboard	Unified console
Switching	Changing providers may require code changes	Change the model name

If you only use Claude and official access works well, direct access is fine. If you need stable access from mainland China and unified multi-model management, a gateway is a better fit.

FAQ

Is the Claude API Key the same as the key used by Claude Code?

Claude Code uses a Claude API key, or a compatible gateway key. A web subscription is not an API key.

Can one key call multiple Claude models?

Yes. The model is specified in the request parameters. See the pricing page for the available models.

Why doesn't the code from the official documentation work?

The usual cause is a mismatch between the Base URL, request headers, and model name. Native and OpenAI-compatible interfaces must be configured separately.

Next steps

If you need stable access from mainland China or a single entry point for multiple models, sign up for ZSQH AI Gateway, create a test key, and complete your first request using this guide. Model names and prices are listed under Model Pricing.