Adding anonymous user authentication to rest resource POST API

Hi Team, 

I have created a rest Resource POST API that will post some content to my application(from frontend created using angular js) that further needed to be stored in DB. Now I need some way to authenticate the anonymous user that fills out the form. 

How I created the POST API: 
https://valuebound.com/resources/blog/how-to-create-custom-rest-resources-for-post-methods-drupal-8

What I tried till now?
I know we can authenticate the API using X-CSRF-Token when we set the basic authentication for the API created and give permission to authenticate user to post from that API. But here the issue is every time end user fills the form I have to login the user using POST API /api/user/login, get the token and pass that token in the POST API I created as X-CSRF-Token, this will create so many session of the user I used to authenticate the API.    

Is there any other way I can use to authenticate anonymous user? Honepot Module or any other module?

Thanks all for your kind support!

Drupal version: 


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