# User & Wallet Identification

### Wallet Management

You have the option to choose between:

* Managing users' wallets yourself
* Or having our API create and manage non-custodial wallets for your users

### User & Wallet Identification

One key aspect of the TokenOS API is how to identify users and wallets.  

**For each endpoint that expects a `userId`, the API accepts three ways to identity unique users:** 

* Email address
* Ethereum address
* User Id, generated by TokenOS 

Each time, we will either retrieve an existing user, or create a new one.