Does Wasabi have a free service tier?

In short, no. Wasabi does offer up to 1 TB of storage for free for up to 30 days for new trial customers. During this 30 day trial period, there is no charge for usage.  After the 30 day trial period (or at any point during the 30 day trial period), a Wasabi user can enter in a credit card to remove the 1 TB limit and continue using Wasabi as a paid subscriber. Once a user enters in a credit card and becomes a paid subscriber, all usage charges become billable from the date the credit card was submitted.