I’d recommend looking at the dangerous things listing for the proxmark, it will be flashed to the latest and correct firmware which can be a headache I learned recently
When your ready to shared your phone contacts via nfc, look for the thread I made and popl it’s so far the best method I’ve found
Yeah, I got you
Implants with Changeable ID
–LF–
–HF–
The rest of the implants have a static ID, which means to use them with compatible access control systems, you need to enroll them like a normal swipe card
General purpose NFC chips with a static ID, but rewritable user memory:
Special use-case chips
Lol you know looking at it now I can see why you’d be confused 
that’s alot, and we haven’t even mentioned the xLEDs and the magnets yet
Thank you for the advice. When I get my NExT installed, I’ll follow your advice on that topic!
This is a really handy breakdown, thanks so much!
So unless I’m misunderstanding - special use-case items aside - it seems like the main difference in programmability is whether or not the chip ID can be changed, but all items have rewriteable user memory.
I was planning on having the NFC function direct the phone (when scanning my implant) to a certain url, I think that is possible right?
I’m hoping to use linktree.ee to list my contact card (social media’s, emails, and phone number) so when the chip is scanned, the user can then have access to all of those. I appreciate it’s not ideal for people to show all their contact info but it’s easy to login and hide certain things too. Could be an easy option for someone like me 
Don’t forget that there’s a major split in the tree also
Frequency
“Standard” rfid is 125khz
Nfc and a lot of the other inteligent stuff if 13.56mhz
You got it.
Basic primer:
LF implants operate at 125kHz, and they’re a legacy technology. They basically only have a simple ID that identifies them to doors and stuff (hence RFID). The xEM and half of the NExT have a special hacked chip that you can change the config and ID of which let’s you clone almost any access card onto those chips using special tools (like a proxmark)
HF implants are the evolution of the technology, and they can be read/written to with a smartphone (NFC). MIFARE was one of the first NFC protocols. It’s janky, doesn’t work with many phones, and has also been cracked like LF so you can change it’s ID if you use implants like the xM1. Newer HF chips are specifically made to be uncloneable for security, so many of those don’t have changing IDs, but they do have user memory where you can put URLs and a bunch of other data that will be read by any phone automatically when presented with the implant.
Perfect! My use case is primarily going to be data/URL sharing to smartphone. I’m not really interested (yet) in using an implant as a substitute for a card or key or as payment method. I thought I’d picked something that’d work solidly for that but got worried that I may have misunderstood how changeable the user memory may be. Seems like I’m all good, though!
Yup you should be good. Here’s a scan of my NExT so you can see the memory structure
This is all super helpful, thanks again for jumping in (and thanks @Mwaters18 for letting me hijack your thread a little)! I’m very excited for when I can order my kit 
Ooorrrrrrr,
In my defense, the next message:
I didn’t realize they were back in stock. Get that one 
I am also new but was kind of scared to speak up. I have done the implant side of things but not as tech-savvy as I feel the average person here is. this post is pretty much me except I am on windows
Well, we are pretty scary. 
Generally I would direct new people to the faq,info and wiki sections, There is a lot of reading, but there is also a lot less chaff to get through to the quality wheat.
Fine by me! It’s helping!! 
One thing I did forget to ask about was bricking, could someone explain what this means and how it happens (so I know how to avoid it!)
Sorry about the long awaited reply, I’m newly registered to the forum and had the newby silencer stuck on me for a number of hours
I knew there’d be someone in the same boat as me!
Another one muzzled by the bot overlords 
In a general high-level answer, bricking happens when try to send info to a device and it gets corrupted. Basically think of it like you are giving someone your address on a phone and the connection cuts out. If you are sending a command to a chip like “your new name is foo” and you lose connection midway. It now doesn’t HAVE a valid name, so the next time a reader asks, it sends gibberish which the reader ignores. The chip is effectively useless because the first step of giving it a new name is asking “what is your name?”
Unfortunately so
So what would be the best way to prevent it from happening? It seems to be one of the scary parts of it because I don’t want to install the chip and then have it become useless if there’s a way to avoid that.
I haven’t run into it personally with implants, but in other electronics it typically happens one of two ways:
User sends the wrong or incomplete command to the chip - Solution is to pay attention and double-check everything before hitting enter. A typo can make a big difference.
The connection between the transmitter and the receiver is lost part-way through the signal and the receiver doesn’t have a way to recover. This is trickier with an implant that we “program” over a wireless signal, but in my very limited experience, sending a message to the chip takes under a second so losing signal part way has not yet been an issue for me… Folks with more experience can maybe set that straight is I’ve just been lucky, but I don’t see very many (if any?) folks on here asking for help with a bricked implant.
Take your time, double-check what you are doing, and read the instructions. If it helps your nerves, maybe check to see if someone on here will be around when you first program the chip Just In Case.
Okay that relaxes me a bit 
thank you! I think I’m going to wait until I get a PM3 to write to the chip or even use the nfc features. Basically just going to have an empty chip in my hand for a while until I’m comfortable I have the equipment and knowledge on how to write to it properly because I’m still not 100% on it
