> ## Documentation Index
> Fetch the complete documentation index at: https://docs.smooth.sh/llms.txt
> Use this file to discover all available pages before exploring further.

# Custom Extensions

> Learn how to use custom browser extensions with Smooth

## Overview

Custom extensions allow you to load your own Chrome extensions into the browser session. This is useful for adding guardrails, taking determistic actions, or for testing extensions.

<CodeGroup>
  ```python Python theme={null}
  # pip install smooth-py
  from smooth import SmoothClient

  smooth_client = SmoothClient(api_key="cmzr-YOUR_API_KEY")

  # Upload a custom extension (must be a .zip file)
  extension = smooth_client.upload_extension(file=open("comic-sans-extension.zip", "rb"))

  # Get the extension ID
  extension_id = extension.id

  # Use the extension in a task
  task = smooth_client.run(
      "Navigate to example.com and take a screenshot",
      extensions=[extension_id]
  )

  # List all uploaded extensions
  extensions = smooth_client.list_extensions()
  for ext in extensions:
      print(f"Extension ID: {ext.id}")

  # Delete extension
  smooth_client.delete_extension(extension_id)
  ```
</CodeGroup>

<Note>
  Extensions must be packaged as Chrome extension .zip files with a valid manifest.json. The extension will be loaded into the browser session and remain active for the duration of the task.
</Note>

## Extension Lifecycle

Extensions are uploaded to Smooth servers and can be reused across multiple tasks. Use `.delete_extension()` to permanently delete it.

```python theme={null}
# Upload once
extension = smooth_client.upload_extension(file=open("my-extension.zip", "rb"))

# Use multiple times
task1 = smooth_client.run("Task 1", extensions=[extension.id])
task2 = smooth_client.run("Task 2", extensions=[extension.id])

# Delete extension
smooth_client.delete_extension(extension.id)
```

## Multiple Extensions

You can load multiple extensions in a single session by passing a list of extension IDs:

```python theme={null}
extension1 = smooth_client.upload_extension(file=open("extension1.zip", "rb"))
extension2 = smooth_client.upload_extension(file=open("extension2.zip", "rb"))

task = smooth_client.run(
    "Your task here",
    extensions=[extension1.id, extension2.id]
)
```