If you want jailbreak iOS 8.1 for free, you must read this simple guide:
1) You must disable “Find iPhone». How: Go to “Settings” > “iCloud” > “Find iPhone” > Off;
2) You must enable “Airplane Mode”;
3) Connect your device to Mac;
4) You must make BackUp. How: Launch iTunes 12 version and make a backup;
5) Download Pangu8 utility (last version) from here
6) Launch “Pangu8”
7) Click “Start Jailbreak”
8) Choosing “Already did”.
9) Wait….
10) Done. You can reboot iPhone, iPad or iPod Touch. After that – you can see Cydia on your jailbroken device.
11) Don’t forget install new Cydia Tweaks and write your experiences here.