# Karrier One API

## Karrier One API

- [Karrier Number System API](https://docs.karrier.one/karrier-one-api/karrier-number-system-api.md): The Karrier Number System API provides a secure way to register users, create and manage approvals, and verify identities and transactions using zk addresses, approval references, and signatures.
- [Number Pre-Registration](https://docs.karrier.one/karrier-one-api/karrier-number-system-api/number-pre-registration.md)
- [User Approvals](https://docs.karrier.one/karrier-one-api/karrier-number-system-api/user-approvals.md): The Karrier Number system can be used to verify a user approves an action.  This enables phone number based 2FA using the blockchain.
- [Karrier Name Service](https://docs.karrier.one/karrier-one-api/karrier-number-system-api/karrier-name-service.md): The Karrier Name Service API allows you to perform forward and reverse lookups between phone numbers and wallet addresses. It supports both single and bulk queries, ensuring efficient integration for
- [Caller Verification API](https://docs.karrier.one/karrier-one-api/caller-verification-api.md): The Caller Verification API enables verification of phone call integrity and user registration by using JWT signatures and mapping phone numbers to object IDs.
- [Call Verification Example Utilities](https://docs.karrier.one/karrier-one-api/caller-verification-api/call-verification-example-utilities.md)
- [Call Verification Flow](https://docs.karrier.one/karrier-one-api/caller-verification-api/call-verification-flow.md): Each phone number can be registered as an NFT, enabling secure verification of calls by mapping identities to digital keys on the Sui blockchain.
- [Global Statistics API](https://docs.karrier.one/karrier-one-api/global-statistics-api.md)