Not just an alternative though.
- Self-hosted
- Unlimited and FREE vs $699 / month
- Create your own agents / integrations
- Process data through shell scripts or JavaScript
- Better filtering
- Liquid templating
- Completely private
I save thousands of dollars by using Huginn.
It's incredibly powerful and quite frankly I don't trust Zapier with my data and visibility of what I'm doing because there are commercial implications.
Run it in the cloud on AWS or on an old box at home.
It's very reliable.