UPDATE (7 July 2021): We've extended the deadline to 30 August 2021 for converting Authtokens to OAuth.

The usage of Authtokens to authenticate API calls is being deprecated on 30 August 2021 across Zoho's Finance suite of products, which includes Zoho Inventory. This change is being done in favor of switching to OAuth 2.0, a more secure and robust protocol.

This means that any of your existing workflows or custom functions, which rely on Authtokens to communicate with Zoho Inventory's APIs will no longer function after 30 August 2021, unless you replace Authtokens with OAuth.

Here are some benefits of OAuth, compared to Authtokens:

• OAuth 2.0 is an industry-standard protocol, which means client applications can communicate with Zoho Inventory's APIs in a generalized manner, instead of figuring out a custom solution.
  

• OAuth provides access to Zoho Inventory's APIs via access and refresh tokens, which do not require you to store your users' Zoho Inventory credentials on your own client application. 
  

• You can specify scopes for access tokens. This means each access token can provide authentication only to the Zoho Inventory APIs which you specify. You can also revoke these access tokens at any time, if necessary.
  

• Access tokens expire after a particular amount of time. This limits your data exposure, in case your client application has been breached. 
  

• How to convert Authtokens to OAuth for self-client applications
  

• How to convert Authtokens to OAuth for redirection-based applications
  

• How to convert existing custom functions (written in Deluge) from Authtokens to OAuth
  

• FAQs on Authtoken to OAuth migration