Hi! I am looking for a load-testing tool which supports more than 20 virtual users in trial version.
In what type of environment? you need to be more specific. If it is a simple server environment? do you need to use physical users, or can you use something like Apache JMeter?
Apache JMeter should be good enough for quick work. However, I did find that Webload ( only supported on windows) to be more sophisticated and a more comfortable option for tests that run for a longer duration. I continued to use both of them depending on my mood swings though.
Prasanna S
I once used Apache jMeter for my diploma thesis. With the possibility for distributed load generation and it's intuitiv and powerful configuration gui, you can simulate a whole lot of "sophisticated" users, using a lot of services, only limited by the amount of computing power (e.g. the number of machines you control). I would also recommend to have a look at it.
This answer only helps, if you are looking for a web testing tool.
You can get 25 virtual users for free at http://browsermob.com. It's a different type of load test though. It uses real browsers to play back every transaction, meaning your scripts can be much simpler and the traffic generated is much more realistic.