Fallout 4 exploits

Armor Mods
You can use Mods from lower tier Armor for higher tier of the same type. Like crafting a Deep-Pocketed Mod for normal Combat Armor and applying it on Heavy Combat Armor without having the perk to craft it for Heavy.

Using the console
By using the "tcl" command in the console while building, you can make your structures  clipping. This can eliminate the gapping in your walls or lower structures into the ground etc. If you place an object while in tcl-mode it becomes "clipp-able" for other structures. You can also pick up structures and fly below the surface where you want to place them. By keeping the structure close to your character, it may follow you under the surface while still being placeable.

Using the "tgm" command while building automatically gives you 999 of every crafting item, and unlocks settlement items that may be restricted by perks, meaning you can effectively build everything.

Menu-, HUD-, inventory-, and radio-related exploits

 * The game allows saving during npc dialogs which makes it easy to reload the game and retry any option which may influence caps, experience, etc. outcome when talking.

VATS Auto-Aim without using AP
Like in Fallout 3, Picking a target in VATS auto-aims the crosshair reticule to that target. This can still be exploited to high degree in close quarters situations (Mole Rat Rush) by:


 * 1) Going into Vats and Highlighting the target or part you want to hit.
 * 2) Cancel out of VATS and repeatedly press the fire button as you do so.
 * 3) Hold the VATS button again to quickly slow down time again and select another target.
 * 4) Repeat.

This is applicable in long-range engagements, but practicality varies. In close quarters, is more consistent.

Physics engine glitches

 * Sometimes VATS will end and seem like the target was missed, but then 2 seconds later the bullet hits. This was tested multiple times at point blank and ranged VATS. The target can be used as a meat shield while the bullet is "frozen"

Infinite XP
After reaching The Prydwen and completing the Fort Strong quest, speak to Proctor Teagan (Weapons Merchant) on the Prydwen. Ask him about extra work and he will give you a mission acquiring crops from the citizens of the Commonwealth. The first location will be a random settlement (Tenpines Bluff and Sommerville Place confirmed) and after completion will award around 100 caps and 125 XP. Asking for extra work again will give you the exact same quest as before, convincing the same settlement to contribute crops. Repeat for unlimited XP and Caps.

After reaching the Brotherhood of Steel's Prydwen, you can go up to Proctor Quinlan and ask to do a scribe escort. After he gives you the quest, you can head out to the flight deck (Where you can see an area near a couple of barrels) and you can kill the scribe in secrecy. Once this is done you can return back to him, saying the scribe died, and it will award you with XP and caps still.

Repeatable Lockpicking
If you happen to find a locked safe right next to a terminal that can also control the lock on the safe, it is possible to pick the lock, use the terminal to lock the safe, then repeat the same process over and over. You will earn the XP for picking the lock every time you do it. This is most useful with a Master lock, and even faster with the unbreakable lockpicks perk. This method cannot however be used to infinitely gain approval with Cait. (It can by quicksaving and reloading in between each try)

Infinite Caps
When trading with a merchant the player buys a large quantity of one type of ammo (ex .308, .45, etc). The players does not complete the trade but instead goes to the to-be purchased ammo in their inventory and gives back one. The player then gives back the rest. Now the player has a single unit of that "shadow" ammo left in their inventory that they can sell back to the trader. After repeatedly selling back that "shadow" ammo for dozens of time, the player can then buy back all those "shadow" ammo sold to trader and in effect double the "shadow" caps you earned. This buy back action makes the whole rip-off process much quicker. The caps the trader owes you can then be traded for the rest of the NPC's inventory.

This can also work to your advantage when buying other goods from a vendor. After completing the first steps, instead of taking all of the vendors caps, the player can select all of the vendor's inventory and then pay the difference with the bullets in the glitch. In this case, it is better to use ammo with a higher value so the purchase process goes quicker.

Note
After selling some ammo back to the trader (about 100) go over to the traders inventory and attempt to buy all of the ammo back and it will keep increasing the caps much faster than selling a few bullets at a time.

Works better if they have over 200 of that type of ammo.

Ammo is sold back to the trader for the value of ammo the trader is selling it for.

Slowly, over time, if the player continues to trade back the ammo, the number of caps being traded will moved to the left of the screen until it's gone.

If the glitch doesn't work for a trader, you can try trading ammo with the trader and try again or use fast travel then try the same trader. In some case this will make the glitch work again.

The type of "shadow" ammo used will be completely traded to the trader thus leaving the player none in inventory. You may deposit the ammo in a nearby container to preserve the ammo you need for guns before trading.

Confirmed to work
Note: This may not list all the ones that work. You can try it with some others.
 * Some settlement store workers
 * Trashcan Carla
 * Arturo Rodriguez
 * Doctor Sun
 * Percy
 * Moe Cronin
 * Proctor Teagan (PC: 5mm only) (Xbox One/PS4: Random, try each ammo until it works)
 * Becky Fallon
 * Solomon
 * Cricket
 * Polly
 * Synth
 * Trudy
 * Lucas Miller
 * KL-E-0
 * Alexis Combes so far only works with .38 ammo not 10mm
 * Myrna

Effect exploits
Bleeding effects stack and do not extend. Meaning high ROF bleed weapons do exponential damage.

Non-player character-specific exploits

 * Dogmeat is able to fetch a variety of items:
 * The Cryolator which normally requires Master lock picking
 * Multiple issues of You're SPECIAL! allowing the character to max out his/her stats.
 * The same exploit performed to duplicate the You're SPECIAL! book will also duplicate other items. Armor however is near impossible to duplicate this way because he simply grabs near the beginning of his animation giving you little chance to grab it before he does.


 * It is possible to have 3 companions by meeting X6 88 to hunt the rogue then simply not going to the targets location he will follow you as a 3rd companion anywhere you go however he will fight with BoS and other various allies, Travis the radio dj can become a permanent follower the same way giving you 3 companions to change their gear drop weapons or armor and have them walk over it they will pick it up rarely.


 * Reseting the Approval Cooldown (Crafting a Mod for Codesworth / Preston or picking a lock for Piper) can be reset by reloading.


 * All companions( expect Dogmeat ) are able to pick things up an infinite amount of items even when their carrying capacity is maxed out. You just simply drop the item you want them to carry and viola. They can now carry more then they are supposed to.
 * (Note) This does not let the companion carry more items through "trade"

Gameplay exploits
Sentry Tower - A exploit used in order to keep a impossible to breach defense. Build a high stairway above your base and place several sentries. Then scrap all wood and the sentries will stay afloat, whenever the base is attacked the sentries will have a 360° view of the base.