In this tutorial you will attach extensions to a profile at creation, add more later, and understand how persistence and compatibility work. Extensions can enhance automation (ad blocking, helper tooling) but must not conflict with fingerprint masking.

## Prerequisites

- Completion of the [Quickstart](../01-getting-started/02-quickstart.md) guide
- Kameleo app running locally (default `http://localhost:5050`)
- Local file paths to valid extension packages (`.crx` for Chromium, `.xpi` for Firefox)

!!!warning Avoid masking overlap
Do not install extensions that alter user agent, canvas, WebGL, timezone, or language. They may create inconsistencies versus Kameleo's coordinated fingerprint.
!!!

## 1. Add extensions at profile creation

+++ Python

```python
from kameleo.local_api_client.models import CreateProfileRequest, UpdateProfileRequest

fp = client.fingerprint.search_fingerprints(browser_product='chrome')[0]
profile = client.profile.create_profile(
    CreateProfileRequest(
        fingerprint_id=fp.id,
        name='with-extensions',
        extensions=['/Users/me/exts/uBlock.crx', '/Users/me/exts/helper.xpi'],
    )
)
print('Created profile with extensions', profile.id)
```

+++ JavaScript

```javascript
const fp = (await client.fingerprint.searchFingerprints(undefined, undefined, "chrome"))[0];
const profile = await client.profile.createProfile({
    fingerprintId: fp.id,
    name: "with-extensions",
    extensions: ["/Users/me/exts/uBlock.crx", "/Users/me/exts/helper.xpi"],
});
console.log("Created profile", profile.id);
```

+++ C#

```csharp
using Kameleo.LocalApiClient;
using Kameleo.LocalApiClient.Model;
using System.Linq;

var fp = (await client.Fingerprint.SearchFingerprintsAsync(browserProduct: "chrome"))[0];

var create = new CreateProfileRequest(
    fingerprintId: fp.Id,
    name: "with-extensions",
    extensions: ["/Users/me/exts/uBlock.crx", "/Users/me/exts/helper.xpi"]
);
var profile = await client.Profile.CreateProfileAsync(create);
Console.WriteLine($"Created profile {profile.Id}");
```

+++

## 2. Add extensions after creation

+++ Python

```python
current = profile.extensions or []
update = UpdateProfileRequest(extensions=current + ['/Users/me/exts/newTool.crx'])
updated = client.profile.update_profile(profile.id, update_profile_request=update)
print('Extensions now:', updated.extensions)
```

+++ JavaScript

```javascript
const updated = await client.profile.updateProfile(profile.id, {
    extensions: [...profile.extensions, "/Users/me/exts/newTool.crx"],
});
console.log("Extensions now", updated.extensions);
```

+++ C#

```csharp
var newList = profile.Extensions?.ToList() ?? [];
newList.Add("/Users/me/exts/newTool.crx");
var update = new UpdateProfileRequest(extensions: newList);
var updated = await client.Profile.UpdateProfileAsync(profile.Id, update);
Console.WriteLine($"Extensions now: {string.Join(",", updated.Extensions)}");
```

+++

## 3. Persistence & export

- Extensions and their storage persist while the profile exists
- Exported profile archives (.kameleo) include installed extensions
- Importing the archive restores them automatically

## 4. Troubleshooting

| Issue                       | Resolution                                                       |
| --------------------------- | ---------------------------------------------------------------- |
| Extension missing on start  | Confirm path exists and has correct file extension (.crx/.xpi).  |
| Browser slow to launch      | Large extensions: remove unnecessary ones or profile separately. |
| Fingerprint mismatch alerts | Remove spoofing extensions that overlap with Kameleo masking.    |