Guest_RikSo there is no free anti spam solution?
I think Anti-Guest addon
is the one could help you. miniBB also provides other methods/alogorithms of protection.
Starting any forums in "opened" mode is a good method. Until they become well-known and nobody spams them, it could mean they are not popular and maybe even useless. So when you feel
they are becoming spammed (and that way they are becoming "known") you may invest a bit and continue to promote them.
If you think more deeper why Captcha is not free, you may discover that miniBB just provides the gradual investment plan. You could install the absolutely free
software and later won't be able to find a person who will maintain or fix it for you free
. You could buy an expensive software which has it all-in-one for the all-in-one huge price, but won't even know why you need this or that feature. With miniBB, you install the basics and pay exactly for what you need.
If you think we could support this project free forever, it's a big mistake. Even if something is free, somebody pays for it.
Also if you think $10 is a big price - welcome to program this addon yourself... it's open source.