> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/sanbuphy/claude-code-source-code/llms.txt
> Use this file to discover all available pages before exploring further.

# Environment Variables

> Environment variables that control Claude Code behavior

Claude Code reads a number of environment variables at startup and throughout a session. These complement `settings.json` for cases where you need machine- or process-level control without modifying files.

<Note>
  `ANTHROPIC_API_KEY` is required when authenticating via API key. Without it (and without an active OAuth session), Claude Code cannot make API calls.
</Note>

## Authentication

| Variable                   | Default | Description                                            |
| -------------------------- | ------- | ------------------------------------------------------ |
| `ANTHROPIC_API_KEY`        | —       | Anthropic API key used for direct authentication       |
| `ANTHROPIC_BASE_URL`       | —       | Override the Anthropic API base URL                    |
| `ANTHROPIC_UNIX_SOCKET`    | —       | Connect to the Anthropic API over a Unix domain socket |
| `CLAUDE_CODE_OAUTH_TOKEN`  | —       | OAuth bearer token injected by the calling environment |
| `AWS_BEARER_TOKEN_BEDROCK` | —       | Bearer token for AWS Bedrock authentication            |

## Cloud provider routing

| Variable                        | Default     | Description                                       |
| ------------------------------- | ----------- | ------------------------------------------------- |
| `CLAUDE_CODE_USE_BEDROCK`       | —           | Route requests through AWS Bedrock                |
| `CLAUDE_CODE_USE_VERTEX`        | —           | Route requests through Google Cloud Vertex AI     |
| `CLAUDE_CODE_USE_FOUNDRY`       | —           | Route requests through Microsoft Azure AI Foundry |
| `AWS_REGION`                    | `us-east-1` | AWS region for Bedrock requests                   |
| `AWS_DEFAULT_REGION`            | `us-east-1` | Fallback AWS region when `AWS_REGION` is not set  |
| `ANTHROPIC_BEDROCK_BASE_URL`    | —           | Override the Bedrock endpoint base URL            |
| `CLOUD_ML_REGION`               | `us-east5`  | Default Vertex AI region                          |
| `CLAUDE_CODE_SKIP_BEDROCK_AUTH` | —           | Skip Bedrock authentication checks                |

### Vertex AI per-model region overrides

Each variable below pins a specific model to a Vertex AI region:

| Variable                          | Model prefix        |
| --------------------------------- | ------------------- |
| `VERTEX_REGION_CLAUDE_HAIKU_4_5`  | `claude-haiku-4-5`  |
| `VERTEX_REGION_CLAUDE_3_5_HAIKU`  | `claude-3-5-haiku`  |
| `VERTEX_REGION_CLAUDE_3_5_SONNET` | `claude-3-5-sonnet` |
| `VERTEX_REGION_CLAUDE_3_7_SONNET` | `claude-3-7-sonnet` |
| `VERTEX_REGION_CLAUDE_4_0_SONNET` | `claude-sonnet-4`   |
| `VERTEX_REGION_CLAUDE_4_5_SONNET` | `claude-sonnet-4-5` |
| `VERTEX_REGION_CLAUDE_4_6_SONNET` | `claude-sonnet-4-6` |
| `VERTEX_REGION_CLAUDE_4_0_OPUS`   | `claude-opus-4`     |
| `VERTEX_REGION_CLAUDE_4_1_OPUS`   | `claude-opus-4-1`   |

## Configuration paths

| Variable            | Default     | Description                                      |
| ------------------- | ----------- | ------------------------------------------------ |
| `CLAUDE_CONFIG_DIR` | `~/.claude` | Override the Claude configuration home directory |

## Operational modes

| Variable                                   | Default | Description                                                                                                                                                                                                                           |
| ------------------------------------------ | ------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `CLAUDE_CODE_SIMPLE`                       | —       | Enable bare/simple mode: skips hooks, LSP, plugin sync, skill directory walk, attribution, background prefetches, and all keychain reads. Auth is strictly `ANTHROPIC_API_KEY` or `apiKeyHelper`. Equivalent to the `--bare` CLI flag |
| `CLAUDE_CODE_REMOTE`                       | —       | Enable remote container mode; sets `max-old-space-size=8192` and enables all hook events                                                                                                                                              |
| `CLAUDE_CODE_REMOTE_SESSION_ID`            | —       | Session ID for the current remote session                                                                                                                                                                                             |
| `CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC` | —       | Disable non-essential network traffic (analytics, telemetry, etc.)                                                                                                                                                                    |
| `CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS`   | —       | Disable experimental beta API features                                                                                                                                                                                                |

## Memory

| Variable                                | Default | Description                                                                                                                                                   |
| --------------------------------------- | ------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `CLAUDE_CODE_DISABLE_AUTO_MEMORY`       | —       | Disable the auto-memory system entirely. Set to `1` or `true` to turn off; `0` or `false` to force-enable even when `autoMemoryEnabled: false` is in settings |
| `CLAUDE_CODE_REMOTE_MEMORY_DIR`         | —       | Override the base directory for remote session memory storage                                                                                                 |
| `CLAUDE_COWORK_MEMORY_PATH_OVERRIDE`    | —       | Full-path override for the auto-memory directory (used by Cowork/SDK)                                                                                         |
| `CLAUDE_COWORK_MEMORY_EXTRA_GUIDELINES` | —       | Extra memory policy text injected into memory prompts                                                                                                         |

## Context and compaction

| Variable                   | Default | Description                                                       |
| -------------------------- | ------- | ----------------------------------------------------------------- |
| `DISABLE_COMPACT`          | —       | Disable context compaction entirely                               |
| `DISABLE_AUTO_COMPACT`     | —       | Disable automatic context compaction (manual compact still works) |
| `DISABLE_BACKGROUND_TASKS` | —       | Disable background task execution                                 |
| `API_MAX_INPUT_TOKENS`     | —       | Override the maximum input token limit                            |
| `API_TARGET_INPUT_TOKENS`  | —       | Override the target input token count for compaction              |

## Thinking and model behavior

| Variable                       | Default | Description                    |
| ------------------------------ | ------- | ------------------------------ |
| `CLAUDE_CODE_DISABLE_THINKING` | —       | Disable extended thinking mode |
| `DISABLE_INTERLEAVED_THINKING` | —       | Disable interleaved thinking   |

## Telemetry and observability

| Variable                      | Default | Description                                                             |
| ----------------------------- | ------- | ----------------------------------------------------------------------- |
| `OTEL_LOG_TOOL_DETAILS`       | —       | Set to `1` to enable full tool input capture in OpenTelemetry telemetry |
| `OTEL_EXPORTER_OTLP_PROTOCOL` | —       | OpenTelemetry exporter protocol (e.g. `grpc`, `http/protobuf`)          |
| `NODE_EXTRA_CA_CERTS`         | —       | Path to extra CA certificate file for custom TLS trust roots            |

## Shell and editor behavior

| Variable                                   | Default | Description                                                             |
| ------------------------------------------ | ------- | ----------------------------------------------------------------------- |
| `CLAUDE_BASH_MAINTAIN_PROJECT_WORKING_DIR` | —       | Reset the working directory to the project root after each Bash command |
| `CLAUDE_CODE_GIT_BASH_PATH`                | —       | Path to git-bash executable (Windows)                                   |
| `EDITOR`                                   | —       | Editor to open when `/memory` is invoked and no `$VISUAL` is set        |
| `VISUAL`                                   | —       | Preferred editor; takes precedence over `$EDITOR`                       |
| `SHELL`                                    | —       | Shell used for command execution                                        |

## Networking

| Variable                                      | Default | Description                                                  |
| --------------------------------------------- | ------- | ------------------------------------------------------------ |
| `CLAUDE_CODE_DISABLE_COMMAND_INJECTION_CHECK` | —       | Disable the command injection safety check (not recommended) |

## How environment variables interact with settings

Environment variables are evaluated at the process level and take effect for the lifetime of the Claude Code process. They are not written to `settings.json`.

The `env` field in `settings.json` lets you set environment variables that are applied to each Claude Code session:

```json theme={null}
{
  "env": {
    "ANTHROPIC_BASE_URL": "https://my-proxy.example.com",
    "NODE_EXTRA_CA_CERTS": "/etc/ssl/my-ca-bundle.crt"
  }
}
```

<Note>
  Truthy values for boolean environment variables are `1`, `true`, `yes`, and `on` (case-insensitive). Falsy values are `0`, `false`, `no`, and `off`. An unset variable is treated as falsy.
</Note>