> ## Documentation Index
> Fetch the complete documentation index at: https://docs.llmeasy.ru/llms.txt
> Use this file to discover all available pages before exploring further.

# How to Configure API Key and Base URL in Claude Code

> Learn how API Key, Base URL, Anthropic-compatible endpoints, and Claude/GPT Key groups fit together when configuring Claude Code.

## Quick answer

When configuring a third-party API in Claude Code, first confirm that the endpoint is Anthropic-compatible. In this documentation, Claude Code uses `https://www.llmeasy.ru`. Do not add `/v1`.

The API Key authenticates the request. The Base URL tells Claude Code where to send model requests. Both must belong to the same provider and protocol.

With the **Claude Key group**, Claude Code usually needs `ANTHROPIC_BASE_URL` and `ANTHROPIC_AUTH_TOKEN`. With the **GPT Key group**, you also need Claude Code model mappings from the setup guide.

## When this matters

* You want Claude Code to use a custom API gateway
* You have an API Key but are unsure which Base URL to use
* Claude Code reports an authentication or endpoint error
* You are choosing between `https://www.llmeasy.ru` and `https://www.llmeasy.ru/v1`
* You need to understand Claude and GPT Key groups

## Key concepts

| Field                    | Meaning                                                                                |
| ------------------------ | -------------------------------------------------------------------------------------- |
| API Key                  | Credential for model API requests                                                      |
| Base URL                 | The API address where requests are sent                                                |
| Anthropic-compatible API | Endpoint that follows Anthropic / Claude request conventions                           |
| OpenAI-compatible API    | Endpoint that follows OpenAI-style conventions, often used by Codex, Cursor, and Cline |
| Model ID                 | The model name or mapping value requested by the tool                                  |

## Recommended setup

Choose the setup path by API Key group.

Claude Key group:

```json theme={null}
{
  "env": {
    "ANTHROPIC_BASE_URL": "https://www.llmeasy.ru",
    "ANTHROPIC_AUTH_TOKEN": "<YOUR_API_KEY>"
  }
}
```

The GPT Key group needs additional Claude Code model mappings. Use the full [Claude Code setup guide](/en/ai-tools/claude-code) instead of copying only this short example.

After editing the config, restart Claude Code and send a short test message. If it fails, first check whether the Base URL was accidentally set to `https://www.llmeasy.ru/v1`.

## Common mistakes

* Adding `/v1` to the Claude Code Base URL.
* Changing the API Key but leaving requests pointed at the default endpoint.
* Treating a GPT Key group model ID as a Claude Key group model.
* Putting an OpenAI-compatible endpoint into Claude Code's Anthropic-compatible fields.
* Defining old environment variables in a shell profile that override the new config.

## About LLMEasy

LLMEasy provides two endpoint types: the Anthropic-compatible `https://www.llmeasy.ru` for Claude Code and the OpenAI-compatible `https://www.llmeasy.ru/v1` for Codex and external tools.

This lets you manage API Keys, balance, and usage history in one dashboard, but it does not change Claude Code's requirement for Anthropic-compatible request formatting.

## Related docs

* [Claude Code setup guide](/en/ai-tools/claude-code)
* [Does Claude Code use a Claude.ai account or an API Key?](/en/faq/claude-code/claude-account-or-api-key)
* [OpenAI-compatible API vs Anthropic-compatible API](/en/faq/concepts/openai-compatible-vs-anthropic-compatible)
* [Why Claude Code uses so many tokens and how to reduce cost](/en/faq/token-cost/claude-code-token-usage)

## References

* [Claude Code LLM gateway configuration](https://docs.anthropic.com/en/docs/claude-code/llm-gateway)
* [Claude Code authentication](https://docs.anthropic.com/en/docs/claude-code/iam)
* [Claude Code model configuration](https://docs.anthropic.com/en/docs/claude-code/model-config)
* [Claude Code setup guide](/en/ai-tools/claude-code)