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

# Introduction to the Watch API

> Identify trustworthy email addresses or phone numbers to mitigate both fake and fraudulent traffic.

<Note>
  To enable the Watch API on your account, [contact us](mailto:support@prelude.so)
</Note>

<Info>
  The [Predict endpoint](/watch/v2/api-reference/predict-outcome) only supports phone numbers for now.
</Info>

## Usage

In order to evaluate the trustworthiness of a phone number, you need to implement complementary
[Predict](/watch/v2/api-reference/predict-outcome) and [Feedback](/watch/v2/api-reference/send-feedbacks)
endpoints. When queried, the Predict endpoint will respond with a prediction of the phone number's
trustworthiness. Indicating whether traffic is expected to be legitimate or suspicious by Prelude’s anti-fraud
system.

The API also supports ingestion of real-time events coming from your systems through its
[Event](/watch/v2/api-reference/dispatch-events) endpoint. Those events should denote your end-users
interactions within your application, and should be accompanied by a confidence level indicating how reliable
you deem the event to be.

### API

The Prelude v2 API is a [REST](https://en.wikipedia.org/wiki/REST) API and uses standard
HTTP features and [statuses](https://developer.mozilla.org/en-US/docs/Web/HTTP/Status).

The current URL is `https://api.prelude.dev/v2`.

### Authentication

To perform requests on the API, you need to provide a **v2** API key in the `Authorization` header.

You can create an API key in the [Dashboard](https://app.prelude.so), under the **API Keys** section of the
settings.

```sh Example request theme={null}
curl --request POST \
     --url 'https://api.prelude.dev/v2/*' \
     --header 'Accept: application/json' \
     --header 'Authorization: Bearer <API_KEY>'
```

### Errors

Prelude uses conventional HTTP [statuses](https://developer.mozilla.org/en-US/docs/Web/HTTP/Status)
to indicate the success or failure of a request:

* Codes in the `2xx` range indicate success.
* Codes in the `4xx` range indicate an error that failed given the information provided (e.g. required parameter was omitted, authentication failed or a rate limit was reached).
* Codes in the `5xx` range indicate an error with Prelude's servers (these are rare).

***

The Prelude API returns errors using a JSON object in the response body with a
machine-readable `code` and a human-readable `message` and a `param` field.

See [Errors](/introduction/errors) for more details as well as a list of all possible error codes.

## Backend SDKs

Integrate effortlessly with Prelude using our Backend SDKs for your platform of choice.

<CardGroup>
  <Card title="Node.js" href="https://github.com/prelude-so/node-sdk" icon="node-js" horizontal>
    Learn how to integrate the Node.js SDK into your application.
  </Card>

  <Card title="Go" href="https://github.com/prelude-so/go-sdk" icon="golang" horizontal>
    Learn how to integrate the Go SDK into your application.
  </Card>

  <Card title="Python" href="https://github.com/prelude-so/python-sdk" icon="python" horizontal>
    Learn how to integrate the Python SDK into your application.
  </Card>

  <Card title="Kotlin/Java" href="https://github.com/prelude-so/java-sdk" icon="java" horizontal>
    Learn how to integrate the Kotlin/Java SDK into your application.
  </Card>

  <Card title="Ruby" href="https://github.com/prelude-so/ruby-sdk" icon="gem" horizontal>
    Learn how to integrate the Ruby SDK into your application.
  </Card>

  <Card title="PHP" href="https://github.com/prelude-so/php-sdk" icon="php" horizontal>
    Learn how to integrate the PHP SDK into your application.
  </Card>

  <Card title="C#" href="https://github.com/prelude-so/csharp-sdk" icon="hashtag" horizontal>
    Learn how to integrate the C# SDK into your application.
  </Card>
</CardGroup>

## Frontend SDKs

Explore how you can enhance your fraud detection process with our [Frontend SDKs](/introduction/frontend-sdks/introduction).

<CardGroup>
  <Card title="Android SDK" href="/introduction/frontend-sdks/android" icon="android" horizontal>
    Learn how to integrate the Android SDK into your application.
  </Card>

  <Card title="iOS SDK" href="/introduction/frontend-sdks/apple" icon="apple" horizontal>
    Learn how to integrate the iOS SDK into your application.
  </Card>

  <Card title="Web SDK" href="/introduction/frontend-sdks/web" icon="code" horizontal>
    Learn how to integrate the Web SDK into your application.
  </Card>

  <Card title="React Native SDK" href="/introduction/frontend-sdks/react-native" icon="react" horizontal>
    Learn how to integrate the React Native SDK into your application.
  </Card>

  <Card title="Flutter SDK" href="/introduction/frontend-sdks/flutter" icon="flutter" horizontal>
    Learn how to integrate the Flutter SDK into your application.
  </Card>
</CardGroup>