## Control which components load

LFX loads all component categories by default. Use environment variables to restrict which categories are available when loading flows.

| Variable | Description |
|---|---|
| `LANGFLOW_COMPONENT_CATEGORY_ALLOWLIST` | Comma-separated list of category names to **include**. If empty, all categories are included. |
| `LANGFLOW_COMPONENT_CATEGORY_BLOCKLIST` | Comma-separated list of category names to **exclude**. Applied after the allowlist. |

Category names are case-insensitive. The virtual keyword `core` in the allowlist or blocklist expands to all core component categories.

Component category names don't always match the labels displayed in the Langflow visual editor.
To view the component categories, see [Bundle list](./extensions-bundle-list).

To restrict components to specific categories:

```bash
export LANGFLOW_COMPONENT_CATEGORY_ALLOWLIST="openai,anthropic,processing,input_output"
uv run lfx serve my_flow.json
```

To exclude specific categories:

```bash
export LANGFLOW_COMPONENT_CATEGORY_BLOCKLIST="prototypes,langchain_utilities"
uv run lfx run my_flow.json "Hello"
```

To allow only core categories:

```bash
export LANGFLOW_COMPONENT_CATEGORY_ALLOWLIST="core"
uv run lfx serve my_flow.json
```