I would recommend a slight rethink.

As someone who produces "not free" software, I'd like to point out some facts.

The ease of use of software is always a factor of the effort involved in writing it. In other words, the easier to use, the harder to write.

Good software (especially software that is easy to use) takes a very long time to produce. It is never free to produce. In the real world time is money. If someone puts months (or years) of their life into writing software and gives it away, then it's exactly like them giving away money.

Support costs. Assuming that you don't want to be left on your own, then you'll need help. even though a community like this is full of people who are willing to help you, the author of the software will always need to have some involvement to keep the product alive.

When you get free software, you are depending on the good will of the Author to supply it and support it. More importantly they need to keep doing that. In many cases peoples lives change, and they no longer have the time that they once had. At this point a free product often dies. A paid product, produced by a company with paid staff recruits a new programmer.

There are many examples of good free software on the web, but given that you're already committing (an often significant amount) money to multiboxing, it doesn't seem sensible to limit your options by refusing to pay the small amount that people charge for multiboxing software.

Speaking for my team, we want to provide an easy to use product, with excellent support, and continue to provide improvements. To do this properly takes a significant amount of money. Ours is a new product and will continue to cost us for at least several months yet. Without charging a small fee, we simply couldn't continue to do what we do.