Yes, Aweber introduced a new Free plan on 14th July 2020.
With the free plan you have access to all the powerful autoresponder features.
The free plan allows up to 500 subscribers, sending up to 3,000 emails monthly.
There free plan includes automations, API integrations, unlimited users and free migration services.
So there is no need to start with a free service like Mailchimp and then migrate to Aweber later.
You can start with the free Aweber plan straightaway.
Get Aweber Free Plan here.