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

# Opt In / Opt Out

> Users must explicitly consent before any bandwidth is shared, and can revoke consent at any time

## What it is

Mellowtel will not share a single byte of bandwidth until the user has explicitly opted in, and the user must always have an obvious way to opt back out. This is a hard requirement of the SDK and a hard requirement of every browser store policy that allows Mellowtel-based extensions.

## Why it matters

It's the user's bandwidth. Anything less than explicit, revocable consent is both unethical and grounds for store removal. The SDK is designed so the *easy* path is also the *compliant* path. If you follow the recommended implementation, you cannot accidentally ship a version that activates without consent.

## How it works

On first install (and on any update that newly introduces Mellowtel) you must show the user a non-dismissible disclaimer that explains what Mellowtel does, then capture their choice. From then on, a settings link must be reachable from somewhere obvious in your UI so they can change their mind.

<Frame caption="Disclaimer example">
  <img src="https://mintcdn.com/mellowtel/-NaMUO-H7VMwBlS7/images/mellowtel_disclaimer.png?fit=max&auto=format&n=-NaMUO-H7VMwBlS7&q=85&s=ab77574d21e0e4879d5f55977eab0223" width="1058" height="898" data-path="images/mellowtel_disclaimer.png" />
</Frame>

You have two implementation options:

1. **Recommended:** open the pre-built Mellowtel opt-in page with `generateAndOpenOptInLink()`. One method call, fully compliant, maximizes opt-in conversion.
2. **Custom UI:** build your own consent surface and call `optIn()` / `optOut()` yourself.

## API surface

| Method                       | Returns            | Use it to                                                               |
| ---------------------------- | ------------------ | ----------------------------------------------------------------------- |
| `generateAndOpenOptInLink()` | `Promise<void>`    | Open the hosted opt-in page (recommended path).                         |
| `getOptInStatus()`           | `Promise<boolean>` | Check whether the user has already opted in.                            |
| `optIn()`                    | `Promise<void>`    | Record consent from your own UI.                                        |
| `optOut()`                   | `Promise<void>`    | Revoke consent from your own UI.                                        |
| `start()`                    | `Promise<void>`    | Begin serving requests after opt-in.                                    |
| `generateSettingsLink()`     | `Promise<string>`  | URL to the hosted settings page so users can change their choice later. |

All methods are accessible from any part of your extension: popup, content script, or background script.

## Recommended implementation

The full integration walkthrough lives in the platform quickstarts. They show where to put the SDK, how to wire it into the install/update lifecycle, and how to test it:

* [Browser plugins quickstart](/browser-plugins/quickstart)
* [Desktop app quickstart](/desktop-app/quickstart)
* [Website quickstart](/website/quickstart)
* [Mobile app quickstart](/mobile-app/quickstart)

In short, after `new Mellowtel(...)` and `initBackground()`, call `generateAndOpenOptInLink()` from your install/update handler. That's it.

## Custom UI

If you want full control over the consent surface, capture the user's choice in your own UI and forward it to the SDK:

```javascript theme={null}
// User agreed
await mellowtel.optIn();
await mellowtel.start();

// User declined or later revoked
await mellowtel.optOut();

// Check status (e.g. to render a toggle)
const hasOptedIn = await mellowtel.getOptInStatus();
```

Whatever UI you build, it must:

1. Be non-dismissible on first install.
2. Default to opted *out* until the user actively agrees.
3. Be re-openable from somewhere obvious in your product so users can change their choice.

## Settings link

Users must always have an easy way to change their settings. Use `generateSettingsLink()` to get a URL to the hosted settings page and place it somewhere persistent: your popup, an options page, an account screen.

```javascript theme={null}
const settingsUrl = await mellowtel.generateSettingsLink();
```

## Announcing Mellowtel to existing users

If you are adding Mellowtel to an extension that already has users, you need to tell them what changed before asking for consent. We provide a [copy-paste announcement template](/concepts/update-announcement) you can adapt.

## Related

* [Privacy](/concepts/privacy): what users are actually agreeing to share.
* [Rate Limiting](/concepts/rate-limiting): how the SDK protects users who do opt in.