Before you decide that this is a scam or fake of some sort, I can assure you it isn't.
I've gotten keys from these sites before and I trust them completely :/

freesteamkeys.me
free-rank.com
facebook.com/LootTootGames
digitalhomicide.ninja

BUT
I'll explain to you the sites.

FREE STEAM KEYS . ME

freesteamkeys.me requires you to do simple tasks such as subscribe to a channel or two, follow people and retweet on twitter, join steam groups, or just simply check out links before gaining access to the key of the game you desire. It works 100% but sometimes it says keys are available even if they aren't, so be quick, there's also an android app for it to notify you of new keys, you should get it (I think it's made by freesteamkeys.me if not download this app:
http://imgur.com/a/kuCI0


FREE - RANK . COM

this isn't just for steam keys. You can get free ranks on servers such as Mineplex I think by doing offers. Note the keys are random for steam and are easy to get BUT I haven't been awarded over half of my points so.. but I did manage to get a horrible game called Why So Evil 2 :Dystopia (if I got it from this site, pretty sure I did)
Sure that game isn't good but, it's free, i think it also has steam trading cards, and yeah.

facebook.com/LootTootGames
DIGITALHOMICIDE.NINJA

Same games, sometimes one or so are different. Check both. Same as FREE STEAM KEYS . ME

https://eu.alienwarearena.com

Free giveaways included. Definitely check it out.

gamekit,com/?reflink=0651-107937654

i know it's a referral link but could you please use it? It's okay if not, just type in gamekit,com if you don't want to. You get keys, games, giveaways, and cs go skins from this site by doing "quests" such as registering and downloading games, inviting friends, etc. I just joined today.
Also, you need to type in one of the links on your browser. Steam won't let me use .com so i had to use ,com