Correct! We have three environments you can send API traffic into - sandbox, development, and production.
Sandbox + development are 100% free to use, development just requires a quick request through the dashboard after signing up for API keys. (https://dashboard.plaid.com/signup)
Sandbox- gives access to sandbox data to test the integration. Development - add up to 100 live bank accounts Production - add as many live accounts with paid account
I went looking for a Go library for your API and the plaid one says it's not maintained/supported anymore. Is there a replacement (third party or not) for it?
we currently don't have an updated official go library for our API, but shoot me an email (charley@plaid.com) and can shoot over some recs for third party libraries