AWS SNS with slack WITHOUT AWS Lambda.
AWS SNS slack notifications

AWS Textract Async:    • Textract tutorial (NEW) (Async vs Syn...  

Steps to follow:

Create slack channel or use existing channel
Create a work flow with selecting Webhook
Create a variable name as "SubscribeURL". The name is very important
Add the above variable in the message body of the workflow
Publish the workflow and get the url
Add the above Url as subscription of the SNS
You will see the subscription URL in the slack channel
Follow the URl and complete the subscription
Come back to the work flow and change the variable to "Message"
The publish the message in SNS. you will see the message in the slack channel.
Enjoy....