CLAUDE_CODE_CLIENT_DATA_URL

Updated October 23, 2026 by Alex Sorokoletov

CLAUDE_CODE_CLIENT_DATA_URL is a Claude Code environment variable: URL of a signed configuration document on downloads.claude.ai with per-model client data; same as --client-data-url, and keeps the URL out of the process list. Claude Code exits if it cannot load the document. Added between v2.1.269 and v2.1.283 and still present in v2.1.310. It is not in the official reference.

How to set it

For one session, export it in the shell that starts Claude Code:

export CLAUDE_CODE_CLIENT_DATA_URL=<value>
claude

To apply it to every session, add it to the env object of a settings file:

// ~/.claude/settings.json
{
  "env": {
    "CLAUDE_CODE_CLIENT_DATA_URL": "<value>"
  }
}

Release notes that mention it

• Claude Code --client-data-url: Signed Model Configuration and --allow-other-models
• claude-code-env-vars-v2-1-303

Related variables

• ANTHROPIC_BASE_URL: Custom endpoint for Anthropic services.
• CLAUDE_CODE_API_BASE_URL: Custom Claude Code API base URL for proxies.
• CLAUDE_CODE_GB_BASE_URL: An internal base URL override, possibly for a "gradebook" or grading service used during internal testing.
• CLAUDE_CODE_MCP_SERVER_URL: The companion to MCP_SERVER_NAME, providing the server endpoint URL.
• CLAUDE_CODE_PROXY_URL: Full proxy URL, injected into the helper subprocess's environment.
• DATABASE_URL
• PIP_INDEX_URL
• CLAUDE_BRIDGE_BASE_URL

Frequently asked questions

All variables, searchable: Claude Code environment variables.