> ## Documentation Index
> Fetch the complete documentation index at: https://circle-devdocs-test-ai-codegen-component.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# User-Controlled Wallets SDKs

Circle's user-controlled wallets SDKs allow for the integration of
user-controlled wallets within your client applications. The SDKs support
various authentications methods to ensure a seamless user experience while using
the wallet.

<Note>
  **Note:** Circle's user-controlled wallets SDKs simplify client-side
  development and are not required for developer-controlled wallets.
</Note>

To build client applications that enable secure, user-controlled wallets, you
must use one of Circle's user-controlled wallets SDKs. Circle supports the
following platforms:

* [Web](/wallets/user-controlled/web-sdk)
* [iOS](/wallets/user-controlled/ios-sdk)
* [Android](/wallets/user-controlled/android-sdk)
* [React Native](/wallets/user-controlled/react-native-sdk)

## Security

The user-controlled wallets SDKs securely manage and communicate with your
server, ensuring that users' keyshares remain exclusively with them and are
never exposed to your server. To maintain security, the SDKs encrypt all request
bodies using an encryption key. This guarantees that users retain full control
over their digital assets in the wallet, with no access to funds by either
Circle or your application.

## Operation

You initialize the SDK by setting the endpoint server. This allows your
application and Circle's API platform to communicate. To simplify the
development of your application, you can use the corresponding server-side
[Node.js SDKs](/sdk-explorer/user-controlled-wallets/Node.js/getting-started) or
[Python SDKs](/sdk-explorer/user-controlled-wallets/Python/getting-started).

Your server retrieves `challengeId` from
[Circle's API platform](/api-reference/wallets/user-controlled-wallets/create-device-token-social-login)
and passes it to the SDK, which then executes relevant operations. Certain
operations may differ based on the authentication method with which you choose
to integrate, for example:

* For social login or email authentication, the SDK can display a confirmation
  UI to your users to preview and confirm the transaction or signature details
* For PIN authentication, the SDK can display a UI that allows your users to
  securely input their PIN and security answers

For more on the SDK design flow including a diagram, see
[SDK Architecture for User-Controlled Wallets](/wallets/user-controlled/sdk-architecture).

## Customizable UI elements

You can customize the styling, layout, and description of your UI modals,
including:

* Title and subtitle - Modify the title and subtitle to reflect your brand
  identity or provide specific instructions.
* Transaction and signature details - Tailor the information displayed on the
  Confirmation UIs to provide context for your users during the signing process.
* Error messages - Customize the error messages displayed to users to provide
  guidance and a personalized experience.
* PIN code input layout - Adjust the layout and styling of the PIN code input
  field to align with your application's design guidelines.
* Question list configuration - Set the list of security questions and allow
  users to choose from a predefined set.

For detailed instructions on customizing UIs for web, iOS, and Android, see the
following docs:

* [Web SDK UI Customizations API](/wallets/user-controlled/web-sdk-ui-customizations)
* [iOS SDK UI Customization API](/wallets/user-controlled/ios-sdk-ui-customization-api)
* [Android SDK UI Customization API](/wallets/user-controlled/android-sdk-ui-customization-api)

## Web SDK

Circle provides the following client-side web SDK to enable integrations with
Circle’s prebuilt UI components to create user wallets securely, send
transactions and more.

<div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-2 gap-4 xl:gap-8 pt-4">
  <Card href="/wallets/user-controlled/web-sdk" title="Web SDK">
    <div className="inline-flex items-center space-x-2 rounded-sm py-2 pr-1 text-blue-400 font-circular-bold hover:bg-blue-50">
      <div>GET STARTED</div>

      <Icon icon="arrow-right" />
    </div>
  </Card>
</div>

## Mobile SDKs

Circle provides the following client-side mobile device SDKs to help you create
native applications for iOS and Android devices and platforms. Mobile SDKs
support only user-controlled wallets.

<div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-2 gap-4 xl:gap-8 pt-4">
  <Card href="/wallets/user-controlled/ios-sdk" title="iOS SDK">
    <div className="inline-flex items-center space-x-2 rounded-sm py-2 pr-1 text-blue-400 font-circular-bold hover:bg-blue-50">
      <div>GET STARTED</div>

      <Icon icon="arrow-right" />
    </div>
  </Card>

  <Card href="/wallets/user-controlled/android-sdk" title="Android SDK">
    <div className="inline-flex items-center space-x-2 rounded-sm py-2 pr-1 text-blue-400 font-circular-bold hover:bg-blue-50">
      <div>GET STARTED</div>

      <Icon icon="arrow-right" />
    </div>
  </Card>

  <Card href="/wallets/user-controlled/react-native-sdk" title="React Native SDK">
    <div className="inline-flex items-center space-x-2 rounded-sm py-2 pr-1 text-blue-400 font-circular-bold hover:bg-blue-50">
      <div>GET STARTED</div>

      <Icon icon="arrow-right" />
    </div>
  </Card>
</div>

## Postman API Suite

Circle’s Postman workspace lets you quickly send requests and learn to use
Developer Services APIs.

<div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-2 gap-4 xl:gap-8 pt-4">
  <Card href="/w3s/postman" title="Postman API Suite">
    <div className="inline-flex items-center space-x-2 rounded-sm py-2 pr-1 text-blue-400 font-circular-bold hover:bg-blue-50">
      <div>GET STARTED</div>

      <Icon icon="arrow-right" />
    </div>
  </Card>
</div>