While playing through the main story arch of Deus Ex Mankind Divided, you can also locate breach software hidden around the world that can help you when it comes to the breach game mode. These will look similar to hacking software, and you can also sell them for credits rather than use them in Breach mode. In total, there are 30 to be found out there.
Prague Day
As soon as you leave your apartment, there is another apartment on the same floor locked by a level 1 keypad. Hack this keypad and you'll be given access, which isn't a restricted zone so you can just walk in without a worry. On the desk with the screen showing nothing but static is this breach software.
The first two of these I'd recommend getting next are both located inside of the Time Machine, where you go to meet Doctor Koller. The first is located in a box outside his office, on top of a bookshelf. The other is located in his dungeon just above his personal laptop. Both should be easy to pick up once you have finished the main story mission to get your augments back in working order.
The next is located in the sewers below Zelen apartments, in Richard's private quarters on the second floor. You'll gain access to this through completing the side quest cult of personality.
Once these are picked up, head to the metro station and we're going to start traveling around a bit. Inside the tourist station in monument station is another breach software behind a level one security door. You can get inside this station by just hoping in through the blown out window just outside the monument station.
Once you've got this, head back into the station and travel to the palisade station, there's a good run of software we can pick up going along from here. There is a pack of breach software located right at the Palisade metro station, at the security office. Oddly enough this isn't a restricted area and you can basically just walk in and grab it from the far desk in the back, on the right hand side.
Once this is grabbed, head just across the street from here to the Tubehouse Electronics store. Downstairs in the demo room there is another breach software up for grabs just sitting on the couch.
Now that you have these two, head around behind the Tubehouse Electronics and you'll find an alley with a wooden fence blocking progress. Hop the fence and you'll find a storage unit with a level 2 keypad, located just inside on the left is a shelf with another pack of software.
Now head over to Sobcheck security and speak to the guy behind the counter here. Give him a dose of neropezine and he'll give you access to his basement where another pack of software is located. It is behind a tripwire system attached to frag grenades though, but if you check out the painting before that, you can move it to expose an unlocked keypad where you can turn off those trip wires. Do so, and head in to find the software on the desk.
Head back outside and take the road to the east until you find the LIMB clinic. There's a few ways to do this, if you have remote hacking you can hack the awning system over the door to open that, or you can carry dumpsters and things over here to climb on. Either way you are going for the archway over the road just to the right of the clinic. Once you get up here you can head into the grate and you'll find a little room at the end, inside a cardboard box is the breach software here.
From here, just a bit more to the east you'll find Pilgrim station, there are many ways of going about getting in here, so it's up to you how you want to do it, but it's located in the red restricted zone is a security room with a guard sitting at a desk. Right on the desk is the breach software you want, so knock out or kill this guy and grab it.
In the coffee shop just to the west of the station you have two options, you can either stack some things outside and jump up onto the balcony where you can remove hack some shutters to open, or you can head inside and down to the basement behind the counter. There's a door downstairs with a level 4 keypad, with the code being 5622. Once inside this room jump on top of the safe and you should be able to make a tricky jump up to the pipes above you. Once you get to the top you'll drop into the apartment where another breach software is located on the bookshelf.
Now in the south east corner of this district, before the red light district, you'll find 'The Music Box' shop. Just outside of it is a manhole leading down into the sewers. Once you're in the sewers, head to the red lights and follow the path to the room filled with gas. Rather than jumping into the gas and possibly dying, look to the left and climb up the barrels here. There are two valves you can close to shut off the gas. Now that it's off you can drop down and find the breach software just beside the TV.
Another is located inside the security room of the casino in the palisade district sewers, you'll be sent here by Doctor Koller to find Otir, so just keep an eye out for this on the desk beside the security terminal while you are there.
Now it's time to check in finally, so head to the TF29 headquarters to advance the story line, and while you are here there is one piece of software located in the TF29 headquarters, specifically in Doctor Fletcher's office inside a level 3 safe.
When you do check in you'll be sent off to the Ruzicka station, where you are also going to find the next pack of software. Head to the server room on the map right after you get off the train, and look between the two boxes in the back corner for this breach software.
Inside the Capek fountain station, in the secure off limits area is where you will find the next one, you can technically hack the front door of this and fight you way in to the server room at the far back at any time, or use the glass shield cloak to hack and sneak in unseen. The software is in the server room sitting on a desk inside here, grab it and get back out of this restricted area.
The Palisade Property Bank has three more sets of breach software. Head down to level 7 of the bank to the executive safes and look for the level 4 keypad on the right hand side, you can use a multitool if required to open this, and you'll find two multitools inside as well as the breach software. From here, head to server room B and go through the vents to get into the office with another safe. The code to this safe is 1114, and the second software is located inside as well as some credits. The last is located inside the CEOs office of the bank, inside of his hidden office. You'll have to solve a mechanical puzzle in order to open the secret door for this and you will be sent here for the side quest 'neon lights'.
At this point, you should have 20 breach software, and two thirds of the way there. You'll have to continue the main story for the rest of them, so do that until you are sent off to Golem city.
Golem city
There are three breach software located in Golem city, so make sure you pick them all up while you're here.
The first is located in the RVAC Row building, you'll end up here during your quest anyway so don't rush it, and you are going to be heading up to level 4 in this building from the elevator on level 2. Turn to the right and enter a room with 505314 on the door, and jump up to the second level in here. Head up the stairs right here and turn around to go all the way to the back of the hallway for a door labeled with 550125. This is some kind of server room, and on the second server rack is the location of this breach software.
The second is found in Arc Headquarters, specifically the second section of the headquarters. Your map is going to refer to this as Ridit station, so if you have that shown you are in the right place. This is located on level 1 of this station, in a room that looks like the security hub for all of the camera systems, with a lot of monitors covering one wall. The software is located on the desk in this room on the far right hand side.
The third is located inside the Arc Headquarters inside Talos Rucker's office, which you will need to talk to for the main story line. After you talk to him you can search his office and it is located right out in the open on his desk.
Prague Night
Once you have returned from Golem city you can access Dvali territory. There is a piece of breach software located in the theater here, just past the manager's office in the security room beside the security terminal. You'll need to hack a level 4 door to gain access to this room.
During the side mission mystery augs you'll be tasked with searching a scientists apartment right beside the TF29 complex once you are back from Golem city as well. Inside the apartment is a level 5 safe with the code of 3608. Pop this open and you'll find this breach software.
Three breach software are located inside the church of the machine god, which you can access through the main story missions if you choose to save Alison to access this early, or if you choose to raid the vault you'll gain access on the third trip back to Prague during the curfew. The first is located inside apartment 93 on the third floor, in the room with the massive amount of server racks you can actually crouch down to sneak under a few of them into a small area with the software sitting out on one of the racks in this area. Apartment 95 has the second software, inside the office with the terminal in it you can interact with a painting on the wall to reveal a safe that isn't even locked. I guess they thought it was hidden well enough to not bother? Anyway, the breach software and some grenades are inside. The last is on the top floor in apartment 96, and is located on a desk just to the right of the bathroom door.
G.A.R.M. Facility
You'll be sent here as part of the main story mission as well, and there are two breach software packs to be found while you are here. The first is located inside hanger one, inside the northwest most little room of the hanger you'll find this on the desk beside a terminal. The second is on the third floor of hanger 2, sitting right out on a desk in the southwest corner of this little area.
Prague - Curfew
By this point, you'll already have all of the breach software, so now it is time to trade it all in. The city is under lockdown though, so you'll have to either be stealthy, or have a firefight with the cops on the streets to get to the tech noir shop. It's closed, but if you break in the clerk behind the counter will still be there, and will happily do business with you and take that software off your hands to unlock booster packs for you in breach mode.