CLAUDE_CODE_CLIENT_CERT

Updated October 13, 2026 by Alex Sorokoletov

CLAUDE_CODE_CLIENT_CERT is a Claude Code environment variable: Path to client certificate for mTLS. Present since v2.1.69 or earlier and still present in v2.1.294. It is listed in the official reference.

Status	Present in v2.1.294
Added	Present since v2.1.69 or earlier
Category	Authentication
Official docs	Listed

How to set it

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

export CLAUDE_CODE_CLIENT_CERT=<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_CERT": "<value>"
  }
}

Release notes that mention it

165 Environment Variables in Claude Code 2.1.69 — What Changed in 50 Versions

Related variables

CLAUDE_CODE_CERT_STORE: Controls which certificate authority store Claude Code uses for TLS verification.
CLAUDE_CODE_CLIENT_KEY: Path to client private key.
CLAUDE_CODE_CLIENT_KEY_PASSPHRASE: Passphrase for encrypted client key.
CLAUDE_CODE_OAUTH_CLIENT_ID: Custom OAuth client ID.
CLAUDE_CODE_CLIENT_KEYPM
CLAUDE_CODE_DESIGN_OAUTH_CLIENT_ID
ANTHROPIC_API_KEY: Primary API key for Claude API.
ANTHROPIC_AUTH_TOKEN: Alternative bearer token; takes priority over API key.

Frequently asked questions

What does CLAUDE_CODE_CLIENT_CERT do?

Path to client certificate for mTLS

Which Claude Code version has CLAUDE_CODE_CLIENT_CERT?

Present since v2.1.69 or earlier and still present in v2.1.294.

How do I set CLAUDE_CODE_CLIENT_CERT?

Export it before starting Claude Code (export CLAUDE_CODE_CLIENT_CERT=value), or add it to the "env" object in ~/.claude/settings.json to apply it to every session.

All variables, searchable: Claude Code environment variables.