sangram said:The safest browser is the teen himself, if he's inclined to it.
Keep in mind that counselling and healthy conversation are the best way to prevent unsafe browsing. Any blocking software is easily bypassed, unless the parent is always sitting with the teen when he browses.
There are a hundred ways for a curious young mind to satisfy itself (which means that all he needs to do is to find somewhere else to see things), and remember that one lusts after what is kept under lock and key.
I would advise to use blockers (I'm sure you'll get a ton of recommendations), but more than that to talk to the child and counsel him on the effects of adult material on children. That is usually much more effective than just expecting software to bring up children. You know what we were all like when we were 14. Do you honestly think a 30 dollar program is going to stop a 14-year old?
Sorry for going a bit off-tangent.
young kid (14 yrs old)