Free safelists can bring you traffic, if you have the right ingredients in place, like a compelling headline and great ad copy. Some safelists have a large proportion of free members or no upgrade option at all. These don't work as well as safelists with more paid members. Paid members have shown that they are willing to spend. Free members are more likely to continue to look for free stuff.
Here's a short directory of some responsive free safelists that also have the option to upgrade. If you want to get the maximum benefit out of these safelists, then consider upgrading. The benefits can be great.
For example, with Business World List, as a free member, you can mail 200 members. But as a pro member, you can mail over 55000 members! And with Free Ad Depot, the email members option is limited to your downline if you're a free member.
This directory includes free safelists that are (or have been) ranked in the top 25 top performing safelists according to TrafficHoopla: