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The purpose of this guide is to help you seamlessly transition from personal token authentication to the more secure OAuth 2.0 with mTLS.

This guide is intended for Wise partners who are the **direct customer of Wise by transacting on their own account** (First Party).

Key Differences between Personal token and OAuth+mTLS Authentication:

* Personal token is replaced with a set of Refresh and Access Tokens
* Token expiration and refresh mechanism


To understand the basics of OAuth 2.0, have a look at our [Security & Access](/guides/developer/auth-and-security) guide.

To understand the basics mTLS, have a look at our [Enhanced Security](/guides/developer/auth-and-security#enhanced-security) guide.

In depth resources:

* [OAuth 2.0](https://oauth.net/2/)
* [Mutual TLS](/guides/developer/auth-and-security/mtls)


## Migration Steps 

We recommend you do the migration in our Sandbox test environment first, and only move to Production once you have verified that all business flows are working.

1. [Integrate and test in Sandbox](/guides/developer/auth-and-security/personal-token-migration/testing-in-sandbox)
2. [Integrate and test in Production](/guides/developer/auth-and-security/personal-token-migration/production-integration)