The Oban folks have done amazing, well-engineered work for years now - it's really the only option for Elixir. That said, I'm very confused at locking the process pool behind a pro subscription - this is basic functionality given CPython's architecture, not a nice-to-have.
For $135/month on Oban Pro, they advertise:
All Open Source Features
Multi-Process Execution
Workflows
Global and Rate Limiting
Unique Jobs
Bulk Operations
Encrypted Source (30/90-day refresh)
1 Application
Dedicated Support
I'm going to toot my own horn here, because it's what I know, but take my 100% free Chancy for example -
https://github.com/tktech/chancy. Out of the box the same workers can mix-and-match asyncio, processes, threads, and sub-interpreters. It supports workflows, rate limiting, unique jobs, bulk operations, transactional enqueuing, etc. Why not move these things to the OSS version to be competitive with existing options, and focus on dedicated support and more traditional "enterprise" features, which absolutely are worth $135/month (the Oban devs provide world-class support for issues). There are many more options available in the Python ecosystem than Elixir, so you're competing against Temporal, Trigger, Prefect, Dagster, Airflow, etc etc.