Claude Code Usage Guide

This guide explains how to point the Claude Code CLI at our reverse proxy endpoint.

Pricing: The Claude Code endpoint is billed at 20% of the official Anthropic API pricing.

Pricing Details (per Million Tokens)

Model	Input	Cache Write	Cache Read	Output
claude-opus-4-6	$1.00	$1.25	$0.10	$5.00
claude-sonnet-4-6	$0.60	$0.75	$0.06	$3.00
claude-haiku-4-5	$0.20	$0.25	$0.02	$1.00

Prices shown are after the 80% discount. Cache Write = 5-minute TTL cache write. Cache Read = cache hit/refresh.

Access: This endpoint is available to subscribed users only. Free-tier users cannot access the Claude Code reverse proxy. Please upgrade your plan to use this feature.

1. Install Claude Code

First, install the Claude Code CLI by following the official documentation:

Installation docs: https://docs.claude.com/en/docs/claude-code/setup

Quick install (macOS / Linux):

Or via npm:

Verify the installation:

2. Configure Claude Code

Claude Code uses two environment variables to determine the API destination:

Variable	Value
`ANTHROPIC_BASE_URL`	`https://api.piapi.ai/v1/claude-code`
`ANTHROPIC_API_KEY`	Your user API key

Three configuration methods are provided below — pick one.

Option A: Use `settings.json` (recommended for project-level config)

Create a .claude/settings.json file in your project directory:

Replace your-api-key with your actual API key.

Why apiKeyHelper instead of ANTHROPIC_API_KEY?
Claude Code's authentication priority (highest → lowest):

apiKeyHelper (shell command output) ← highest

ANTHROPIC_API_KEY environment variable

Stored OAuth token (from claude login) ← lowest

If you have ever run claude login, an OAuth token is stored in ~/.claude/.credentials.json. This token silently overrides ANTHROPIC_API_KEY, causing requests to be sent with the wrong credentials. Using apiKeyHelper avoids this problem entirely.

This method takes effect automatically whenever you run claude inside the project directory — no shell rc changes needed.

Option B: Use a `.env` file (recommended for long-term use)

Option C: Direct `export` (temporary / per-session)

Run this in the terminal where you want to use Claude Code:

The variables are lost when the terminal closes — useful for quick testing or switching providers.

3. Verify the Configuration

Confirm the environment variables are set:

Both should print the values you configured.

Then start Claude Code to test:

If you get a normal model response, the configuration is working.

4. Switching Models

Inside a Claude Code session, type the /model command to switch between Claude models:

/model

Follow the prompts to choose a model.

5. FAQ

Q: I get `403 "This endpoint is reserved for Claude Code CLI only"`

Requests must be made through the official claude CLI. Custom curl scripts or third-party SDKs are not allowed to call this endpoint directly.

Q: How do I switch back to the official API?

Unset the environment variables:

Or comment out the two lines in ~/.claude/.env and re-source your shell rc file.

6. Support

If you run into any issues, please contact technical support.

Claude Code Usage Guide

Pricing Details (per Million Tokens)#

1. Install Claude Code#

2. Configure Claude Code#

Option A: Use settings.json (recommended for project-level config)#

Option B: Use a .env file (recommended for long-term use)#

Option C: Direct export (temporary / per-session)#

3. Verify the Configuration#

4. Switching Models#

5. FAQ#

Q: I get 403 "This endpoint is reserved for Claude Code CLI only"#

Q: How do I switch back to the official API?#

6. Support#