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Authentication & API Access

ANTHROPIC_API_KEY

Section titled “ANTHROPIC_API_KEY”
  • Type: String
  • Default: Unspecified
  • Precedence: Fallback when ANTHROPIC_AUTH_TOKEN is not set
  • Description: Primary API key for Anthropic’s Claude API. Used as the fallback authentication method when no OAuth token is configured.
  • Example: export ANTHROPIC_API_KEY=sk-ant-abcdef123456
  • See also: ANTHROPIC_AUTH_TOKEN, CLAUDE_CODE_OAUTH_TOKEN

ANTHROPIC_AUTH_TOKEN

Section titled “ANTHROPIC_AUTH_TOKEN”
  • Type: String (bearer token)
  • Default: Unspecified
  • Precedence: Takes priority over ANTHROPIC_API_KEY for authorization headers
  • Description: Alternative bearer token for Anthropic services. When set, used in preference to ANTHROPIC_API_KEY.
  • Example: export ANTHROPIC_AUTH_TOKEN=Bearer eyJhbGc...
  • See also: ANTHROPIC_API_KEY, CLAUDE_CODE_OAUTH_TOKEN

ANTHROPIC_BASE_URL

Section titled “ANTHROPIC_BASE_URL”
  • Type: URL
  • Default: https://api.anthropic.com
  • Description: Custom base URL for Anthropic API endpoints. Overrides the default endpoint. Useful for private deployments or proxy routes.
  • Example: export ANTHROPIC_BASE_URL=https://internal-api.company.com/anthropic
  • See also: CLAUDE_CODE_API_BASE_URL

CLAUDE_CODE_API_BASE_URL

Section titled “CLAUDE_CODE_API_BASE_URL”
  • Type: URL
  • Default: Falls back to ANTHROPIC_BASE_URL, then https://api.anthropic.com
  • Precedence: Checked before ANTHROPIC_BASE_URL
  • Description: Claude Code–specific alternative base URL for the Anthropic API.
  • Example: export CLAUDE_CODE_API_BASE_URL=https://api.internal.company.com
  • See also: ANTHROPIC_BASE_URL

ANTHROPIC_CUSTOM_HEADERS

Section titled “ANTHROPIC_CUSTOM_HEADERS”
  • Type: String (newline-separated Key: Value pairs)
  • Default: Unspecified
  • Description: Custom HTTP headers to include in all API requests. Newline-separated; each line is a header name and value.
  • Example: export ANTHROPIC_CUSTOM_HEADERS=$'X-Custom-Header: value1\nX-Another: value2'

ANTHROPIC_BETAS

Section titled “ANTHROPIC_BETAS”
  • Type: String (comma-separated list)
  • Default: Unspecified
  • Description: Comma-separated list of beta feature headers to include in API requests. Appended to internal beta flags managed by Claude Code.
  • Example: export ANTHROPIC_BETAS=interleaved-thinking-2025-05-14,prompt-caching-2024-07-16

ANTHROPIC_UNIX_SOCKET

Section titled “ANTHROPIC_UNIX_SOCKET”
  • Type: String (filesystem path)
  • Default: Unspecified
  • Description: Unix socket path for Anthropic API connections. Used with Bun runtime for direct socket communication instead of HTTP. Advanced use case.
  • Example: export ANTHROPIC_UNIX_SOCKET=/tmp/anthropic-api.sock

ANTHROPIC_LOG

Section titled “ANTHROPIC_LOG”
  • Type: String (log level)
  • Default: Unspecified
  • Description: Anthropic SDK internal logging level. Controls verbosity of the underlying Anthropic SDK, not Claude Code itself.
  • Example: export ANTHROPIC_LOG=debug

API_TIMEOUT_MS

Section titled “API_TIMEOUT_MS”
  • Type: Integer (milliseconds)
  • Default: 600000 (10 minutes)
  • Description: API request timeout. Shown in timeout error messages with a suggestion to increase if needed. Must be a positive integer.
  • Example: export API_TIMEOUT_MS=1200000 # 20 minutes

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