I was asked if I could program something for vBulletin. As I never programmed something for vBulletin I started to search for documentation and tutorials. Unfortunately I wasn’t very lucky.
The most promising thing I found was this, but it looks like it was autogenerated and isn’t very helpful for beginners. After some more searching I found a collection of tutorials in the vBulletin forums (3.5/3.6 Tutorial index), but the forum hides all code from non-members and I don’t think I get an account without buying a vBulletin licence.
Is there a way to find if what I want to do is possible and more or less easy to integrate into vBulletin, without buying a licence?
vBulletin is particularly difficult to code for without a copy of their source. There isn’t enough information in the documentation to allow you to code with confidence. More importantly, you have no way of testing your code.
I don’t know about the newer licenses, but I think some of the older ones are transferable. You might be able to pick up a second-hand license for a reasonable price if a new license is outside your budget. If you go down this route, be careful of code changes between vB 3.7, 3.8 and 4.0.