CLAUDE_BASE

Updated October 13, 2026 by Alex Sorokoletov

CLAUDE_BASE is a Claude Code environment variable: Likely overrides the base URL or base configuration path for Claude Code. This is a compact alternative to the more specific CLAUDE_CODE_API_BASE_URL — potentially used internally or as a shorthand for environments where a single base path controls both API routing and local configuration resolution. Added in v2.1.92 and still present in v2.1.294. 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_BASE=<value>
claude

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

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

Release notes that mention it

• Claude Code v2.1.92 — 5 New Environment Variables: Proxy Simulation, Fast Mode Bypass, and Remote Session Naming
• Claude Code Version Tracker: Undocumented Env Vars, Feature Gates & Models

Related variables

• CLAUDE_CODE_BASE_REF: Git base ref for diff operations.
• CLAUDE_CODE_BASE_REFS: Specifies base git references (branches, tags, or SHAs) for diff comparison when Claude Code operates in a worktree or feature branch.
• ANTHROPIC_BETAS: Comma-separated beta feature headers.
• ANTHROPIC_CUSTOM_HEADERS: Custom HTTP headers (newline-separated Key: Value).
• ANTHROPIC_FEDERATION_RULE_ID
• ANTHROPIC_ORGANIZATION_ID
• ANTHROPIC_WORKSPACE_ID
• BETA_TRACING_ENDPOINT: Custom endpoint for beta tracing.

Frequently asked questions

All variables, searchable: Claude Code environment variables.