A guide for All 24 Key Data Collectible Locations & Solutions in Watch Dogs 2. Finding all of them unlocks the Researcher trophy / achievement. It is also needed to buy certain skills and upgrades.

The Key Data locations are shown to you in-game and are easy to find. Open the research App on your phone and press Triangle (PS4) / Y (XB1) on a key data skill. It will show you the rough search area on the map, not always the exact location. You can use the Quadcopter and press Right Stick to scan the world for nearby collectibles.

Figuring out the solutions to these puzzles is the harder part. Many of them require the RC Jumper or Quadcopter (RC Jumper is one of the first story unlocks, Quadcopter must be bought in Hacker HQ).
One key data requires the skill "Environmental RC" (costs 2 research points). All the others can be found without the use of skill upgrades.

You can reach every key data very early in the game, after you unlock the research app. They will be saved instantly when you pick them up. Nothing is missable.
In the research app you can see which ones you've found.

TIMELINE (with category & skill name):

REMOTE CTRL:

#1 - Speed Boost - 0:05
#2 - Enhanced Spring - 1:08
#3 - Expert RC Engineering - 2:02
#4 - Remote Gadgets - 2:36

VEHICLE HACKING:

#5 - Engine Override - 3:10
#6 - Massive Vehicle Hack - 3:40
#7 - Botnet Savings: Vehicle Hacks - 4:34
#8 - Chopper Retreat Exploit - 5:13

SOCIAL ENGINEERING:

#9 - Gang War - 5:57
#10 - Botnet Savings: Personal Devices - 6:34

CITY DISRUPTION:

#11 - Security System Shutdown - 7:13
#12 - Botnet Savings: City Hacking - 7:51
#13 - Massive System Crash - 9:51
#14 - System Crash Upgrade: Blackout - 11:38

TINKERING:

#15 - Tweaked Blast - 12:15
#16 - Explosive Optimization - 12:44
#17 - Expert Tinkering - 13:44
#18 - Electro Shock Optimization - 14:26

BOTNETS = None

MARKSMANSHIP:

#19 - Stun Amp Up - 16:09
#20 - Fast Trigger Finger - 20:06
#21 - Steady Hands - 20:30
#22 - Keen Eye - 20:55
#23 - Strong Grip - 21:28
#24 - Target Weakness - 21:52

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