Sales Tax API
The Free-To-Use API by avalara has some restrictions. Usage of this API is subject to rate limits. Users who exceed the rate limit will receive HTTP response code
429 - Too Many Requests. The requirement for this API is to create an avalara free trail account. You can create a free account using this link create free account.
Once you have filled the form from above link, you will get an e-mail containing temporary credentials to login the avalara account. The e-mail will look something like this: