TL;DR. Compare your serial here to know if your Switch is patched or not:

Serials beginning with XAW1:
XAW1007400X and below are safe to buy
XAW1007500X and above not safe to buy, possibly patched
XAW1012000X and above definitely patched

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Serials beginning with XAW4:
XAW4001100X and below are safe to buy
XAW4001200X and above not not safe, possibly patched
XAW4003000X and above definitely patched

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Serials beginning with XAW7:
XAW7001780X and below are safe to buy
XAW7001790X and above not safe to buy, possibly patched
XAW7003000X and above definitely patched

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Serials beginning with XAJ1:
XAJ1002000X and below are safe to buy
XAJ1002100X and above not safe to buy, possibly patched
XAJ1003000X and above definitely patched

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Serials beginning with XAJ4:
XAJ4004600X and below are safe to buy
XAJ4004700X and above not safe to buy, possibly patched
XAJ4006000X and above definitely patched

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Serials beginning with XAJ7:
XAJ7004000X and below are safe to buy
XAJ7004100X and above not safe to buy, possibly patched
XAJ7005000X and above definitely patched

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Serials beginning with XAW9:
Refurbished Consoles directly from Nintendo, no informations, but
very possible all patched.

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Serials beginning with XAK:
No informations available, since those are only sold in Korea (?)

F.A.Q:

Q: The Serial of my Switch begins with four or more zeros, what does it mean?
A: Those Switches are all unpatched and can be bought without hesitation. Leading zeros just
mean that actual serial number that follows is very small, so the switch is rather old.

Q: My Serial is in the orange region, which says that it is possibly patched, what does that mean for me?
A: This means that it is not possible to tell from your serials number if your Switch is patched or not. It has
to do with the fact that after patched units were first produced, Nintendo also produced unpatched units. That
leads to an overlap.

Q: I've already bought a Switch in the orange region, what should I do?
A: It depends. If it is still sealed and you have the possibility to return it, you should probably try to get a Switch
in the green region. If you can't return it, just try and see for you self if it is patched or not. It is not possible
to brick/harm/destroy the Switch with this method:
https://gbatemp.net/threads/a-defin...atched-or-not-purchases-after-07-2018.512018/

Q: My Switch is definitely patched, what should I do now?
A: You have two options:
1) Wait till a hacker finds a way to hack a patched Switch unit. We don't know when or if they'll find a solution. You need to be patient.
2) Sell the Switch and get an unpatched one

Q: I found a Switch with serial XYZ and it is really close to the XYZ+1 one I found in the spreadsheet, which was unpatched. Should I buy it?
A: This is missleading. Yes, it might be unpatched, but serial XYZ could also be in the orange region. That would mean the guy on the spreadsheet got an
unpatched one, while yours could be patched. Always compare the serials to the colour regions above, never to a single serials in isolation.

Q: I have read this guide and I know that the guide said my switch is unpatched/possibly patched/patched. Should I still ask a question about if anyone has information
about my Switch?
A: No. The guide is up-to-date and the borders are trusted. You can post it of course, but don't expect any new informations.

Q: I have seen other guide similar to this guide with slightly different borders, what's the deal with that?
A: Basically, other sites copied the informations and posted them on their side without giving credit. I don't care. What
I do know is that this guide is the most accurate one out there. Feel free to correct me if I am wrong.

Q: I found a bundle XYZ. Is it patched or unpatched?
A: Bundles don't play any role whether a Switch is patched or unpatched. Always go after serials number.

Q: I read everything and I am still confused about the guide. Please help?
A: If you have read everything twice you have my permission to ask in this thread. Beware of snarky comments.

Q: What about XAW9, XAK and other serials numbers not in the guide?
A: ¯\_(ツ)_/¯ I don't know. I don't work for Nintendo, nor do I have any insider knowledge. I just gather that the people have collected in this thread
and the spreadsheet. There is to little information about those to make good predictions.

Q: Where can I find the serial number on the Box?
A: Have a look in the spoiler. The box has a little cut-out where the serial should be visable.

Warning: Spoilers inside!

Q: I want Switch with a specific firmware preinstalled, can you help me out?
A: Compare the serial to the list inside this spoiler.

Warning: Spoilers inside!

1.0.0

XAW100006 - XAW100128

XAW700014 - XAW700047

XAJ100022 - XAJ100042

XAJ400004 - XAJ400091

XAJ700002 - XAJ700065


2.1.0

XAW100139 - XAW100140

XAW700049 - XAW700050

XAJ400105 - XAJ400136

XAJ700070 - XAJ700085


2.2.0

XAW100158 - XAW100173

XAJ400105 - XAJ400174

XAJ700090 - XAJ700093


2.3.0

XAW100175 - XAW100214

XAW400008 - XAW400016

XAW700053 - XAW700055

XAJ100086

XAJ400105 - XAJ400155

XAJ700098 - XAJ700132


3.0.0

XAW100154 - XAW100230

XAW400017 - XAW400033

XAW700056 - XAW700081

XAJ100109 - XAJ100138

XAJ400169 - XAJ400191

XAJ700133 - XAJ700153


3.0.1

XAW100218 - XAW100320

XAW400028 - XAW400036

XAJ100121 - XAJ100158

XAJ400197 - XAJ400267

XAJ700150 - XAJ700199


3.0.2

XAW100294 - XAW100442

XAW400042 - XAW400081

XAJ100175 - XAJ100182

XAJ400267 - XAJ400281

XAJ700197 - XAJ700319


4.0.1

XAW100439 - XAW100552

XAW400081 - XAW400090

XAJ100248 - XAJ100252

XAJ400309 - XAJ400372

XAJ700304 - XAJ700371

4.1.0

XAW100572 - XAW100940

XAW400088 - XAW400154

XAW700097 - XAW700183

XAJ100172 - XAJ100277

XAJ400344 - XAJ400605

XAJ700319 - XAJ700465


5.10

XAJ700417 - XAJ700437

Q: I want to help, what can I do?
A: If you have all informations about your Switch, fill out the form below and post it here.

Serial:
Serial on device matches serial on box:
Region:
Firmware:
Color option:
Store:
Was a bundle (if yes, which):
Purchase date:
Fusée Gelée works:

If you know with which Firmware your switch came out of the box, please fill in those fields.




According to CTCear, here are some information about the Switch serial numbers:

For example: XAJ70002712345

X: Product of NX line
A: Switch Hardware
J70: Assembly line
The following numbers are probably a consecutive number. So the Switch in the example is Switch number 2712345.

Here is a quick guide on how to check the Firmware without going through the initial setup.

Xplic1T created a spreadsheet that contains all information that we gathered in this thread in more detail then the OP.
You can view it here
Feel free to edit the spreadsheet with more informations