# Ways to register users
To effectively target and engage users through Pushwoosh, it's crucial to ensure that user devices are properly registered and your data is synchronized. Pushwoosh offers several ways to register users, depending on whether you're integrating a new app or bringing over an existing audience.
## New users
### Register via SDK or API
For mobile apps, Pushwoosh SDK integration is the recommended way to register devices and synchronize data automatically. It calls the registerDevice API method internally and can also register phone numbers for SMS and WhatsApp notifications.
For websites, integrate the [Web Push SDK](/developer/pushwoosh-sdk/web-push-notifications/web-push-sdk-30), then set up a custom or default [Subscription Prompt](/product/messaging-channels/push-notifications/subscription-prompt) so visitors can opt in to push notifications.
[Learn more about Pushwoosh SDK](/developer/pushwoosh-sdk/pushwoosh-sdk-overview)
For more advanced registration and sync scenarios, use the Pushwoosh API instead.
### Use a third-party integration
Connect a platform you already use to sync users and data with Pushwoosh automatically.
## Importing your existing user base
If you're working with large sets of pre-existing data, you can import it into Pushwoosh instead of collecting it from scratch.
### Mobile push subscribers
If you're migrating from another push provider, import your existing push subscriber base from a CSV file. Tokens from your previous provider keep working as long as the app still uses the same APNs key, Firebase project, or HMS credentials, so users don't need to reinstall the app or grant permission again.
For migrations this self-serve import doesn't cover, contact us via the [Contact Us form](https://help.pushwoosh.com/hc/en-us/requests/new) and provide a sample of your user base. Our team will review the data format and assess whether the migration is feasible.
### Web push subscribers
Web users cannot be imported due to technical limitations. Different push providers use varying payload formats and platform configurations, making importing web users ineffective. As a result, the imported user base would either be invalidated or receive incorrect or blank content.
However, web users who have already given permission to receive push notifications for your website can be resubscribed.
### Email, SMS, WhatsApp, and Viber contacts
Import contacts from a CSV file to register email, SMS, WhatsApp, and Viber subscribers in one pass.