Disclaimer: please note this property is sent by the browser and can thus be faked, just like user agent strings. Never rely on the navigator object to be completely accurate.
navigator.platformindicates the machine type for which the browser was compiled.
This basically means the property can return Win16 when the user is running a browser compiled for 16-bit, even though the user is on a 32-bit or 64-bit Windows machine.
Of course W3Schools lists the old definition (I'm not even gonna link to them). W3 and MDN have agreed on a different definition though:
navigator.platformrepresents the platform on which the browser is executing.
Still, this definition is a bit vague. A decade ago a 'platform' would either be a CPU architecture or an operating system. In recent years handheld and media devices can be platforms too.
It seems like we're a bit luckier when it comes to handheld and media devices. As you've already stated in your question, the iPhone, iPod and iPad each got a unique value, even though they're all running the same operating system. All of Nintendo's and Sony's devices are returning unique values too. So only now navigator.platform is starting to look interesting.
But then Opera Mini for iPhone comes along, messing things up again. Opera Mini actually returns a code engine version number, which is a completely different interpretation of platform than anything we've come across so far. So now we're back where we started and we start to understand why there's so little information on this subject out there.
Even though the interpretations vary and I don't have a complete answer for you, I did feel like I should add my 2 cents for anyone else out there researching the navigator.platform property.
Android
It's really hard to test for Android devices. Android devices will return Android just as often as some version of Linux. For example on a Nexus 5 phone, both the Android browser and Chrome return Linux armv7l. In rare cases Android devices can even return null (instead of undefined).
Android (2008)Linux: see notes abovenullApple
As far as iOS goes: Safari, Chrome and Mercury agree, but Opera messes things up.
iPhone (2007)iPod (2007)iPad (2010)iPhone Simulator: simulator shipped with XcodeiPod Simulator: simulator shipped with XcodeiPad Simulator: simulator shipped with XcodeMacintoshMacIntel: Intel processor (2005)MacPPC: PowerPC processorMac68K: 68000 processorPike v7.6 release 92: Opera Mini 5 on any iPhone (2009)Pike v7.8 release 517: Opera Mini 7 on any iPhone (2012)BlackBerry
BlackBerry (2003)FreeBSD
FreeBSDFreeBSD i386: x86 (IA-32) processorFreeBSD amd64: AMD x86-64 processorLinux
Seriously unreliable because so many platforms are built on this. For example, Chrome on ChromeOS or Linux x86-64 both return Linux i686 as that's what they were compiled for.
Note Linux ARM lists architecture flags, e.g. armv5tej would denote a v5 ARM architecture with Thumb support ('T'), a DSP instruction set ('E'), and Jazelle support ('J').
LinuxLinux aarch64Linux armv5tejlLinux armv6lLinux armv7lLinux armv8lLinux i686Linux i686 on x86_64Linux i686 X11: based on X11 Window SystemLinux MSM8960_v3.2.1.1_N_R069_Rev:18: Sony Xperia VLinux ppc64Linux x86_64Linux x86_64 X11: based on X11 Window SystemMicrosoft
Even on a 64-bit Windows 8 they all stick to Win32.
OS/2 (1994†)Pocket PCWindowsWin16: Windows 3.1x (1992†)Win32: Windows 95 and upWinCEMozilla (Firefox OS)
An empty string is returned in the web browser on Firefox OS. See this bug report.
KaiOS
The web browser on KaiOS (based on Firefox) also returns the empty string (same as Firefox OS). See this bug report.
Nintendo
New Nintendo 3DS (2014)Nintendo DSi (2008)Nintendo 3DS (2011)Nintendo Wii (2006)Nintendo WiiU (2012)OpenBSD
OpenBSD amd64Symbian / S40
Nokia_Series_40 (1999†)S60 (2002†)Symbian: Opera on SymbianSymbian OSPalm
PalmOS (1996)webOS (2009)Solaris
SunOSSunOS i86pcSunOS sun4u: SPARC processorSony
PLAYSTATION 3 (2006)PlayStation 4 (2013)PSP: PlayStation Portable (2004)Various
HP-UX: Hewlett-Packard UniXmasking-agent: value changes to this when using Masking Agent for FirefoxWebTV OSX11: X11 Window SystemHave a device that's not on this list? Please leave a comment listing your device's properties and its navigator.platform value (feel free to use this JSFiddle to find the value).
Hope this helps.
I can add to this list with definitive values for specific devices I've tested.
Where the string is Linux armv7l, it ends in a lowercase L (for "Linux, presumably?), rather than being a number 1 or lowercase I.
For the iOS devices, testing was performed in Safari. For the Android devices, testing was performed in the stock browser, or Chrome if no stock browser was installed.
Of the Windows tablet devices, the Nokia Lumia was running Windows RT 8.1 with IE 11.0.9600.16476, and the MS Surface was running Windows 8.1 Pro with IE 11.0.9600.16438.
Of the Windows phones devices, the Nokia Lumia was running Windows Phone 8.1 and IE 11.
Phones
Device OS window.navigator.platform
---------------------------------------------------------------------------
iPhone 4 iOS 7.1 iPhone
iPhone 5 iOS 7.1.1 iPhone
iPhone 5c iOS 7.1 iPhone
iPhone 5s iOS 7.1 iPhone
Samsung Galaxy S2 Android 4.1.2 Linux armv7l
Samsung Galaxy S3 Mini Android 4.1.2 Linux armv7l
Samsung Galaxy S3 Android 4.3 Linux armv7l
Samsung Galaxy S4 Android 4.4.2 Linux armv7l
Samsung Galaxy Note 3 Android 4.4.2 Linux armv7l
Samsung Galaxy S6 Android 5 Linux aarch64
Nexus 4 Android 4.4.2 Linux armv7l
Nexus 5 Android 4.4.2 Linux armv7l
HTC One Android 4.4.2 Linux armv7l
Sony Xperia Z Android 4.2.2 Linux armv7l
Motorola Moto G Android 4.4.2 Linux armv7l
Nokia Lumia 1520 Windows 8.1 Win32
Tablets
Device OS window.navigator.platform
---------------------------------------------------------------------------
iPad 2nd generation iOS 6.1.3 iPad
iPad 2nd generation iOS 7.0.3 iPad
iPad 4th generation iOS 6.1.2 iPad
iPad 4th generation iOS 6.1.3 iPad
iPad mini (non retina) iOS 6.1.3 iPad
iPad mini (retina) iOS 7.0.3 iPad
Samsung Galaxy Tab 2 7" Android 4.0.3 Linux armv7l
Samsung Galaxy Tab 3 7" Android 4.1.2 Linux armv7l
Samsung Galaxy Tab 3 Android 4.2.2 Linux i686
Samsung Galaxy Note 10.1 (2012) Android 4.1.2 Linux armv7l
Samsung Galaxy Note 10.1 (2014) Android 4.3 Linux armv7l
Nexus 7 (2012) 7" Android 4.4.3 Linux armv7l
Nexus 7 (2013) 7" Android 4.3 Linux armv7l
Nexus 10 Android 4.4.2 Linux armv7l
Lenovo Yoga Android 4.2.2 Linux armv7l
Sony Xperia Z Android 4.3 Linux armv7l
Tesco Hudl 7" Android 4.2.2 Linux armv7l
Kindle Fire 7" (2012) Unknown Linux armv7l
Kindle Fire HDX 7" (2013) Unknown Linux armv7l
Asus Transformer Pad TF300T Android 4.0.3 Linux armv7l
Nokia Lumia 2520 Windows RT 8.1 Win32
MS Surface Tablet Pro Windows 8.1 Pro Win64
Desktop PC (HP) Windows 7 Ent. Win32
Desktop PC (iMac) OSX 10.8.5 MacIntel
I could not post a comment, so I leave these ones I think are not mentioned above:
+-----+--------------+--------------------------------------+
| iid | item | value |
+-----+--------------+--------------------------------------+
| 448 | nav_platform | Linux armv7l |
| 454 | nav_platform | ARM |
| 455 | nav_platform | Linux x86_64 |
| 457 | nav_platform | PlayStation 4 |
| 459 | nav_platform | masking-agent |
| 460 | nav_platform | OpenBSD amd64 |
| 464 | nav_platform | FreeBSD amd64 |
| 465 | nav_platform | Linux armv5tejl |
| 466 | nav_platform | Symbian OS |
| 467 | nav_platform | New Nintendo 3DS |
| 470 | nav_platform | Linux armv6l |
| 471 | nav_platform | FreeBSD |
| 472 | nav_platform | Symbian |
| 473 | nav_platform | Linux MSM8960_V3.2.1.1_N_R069_Rev:18 |
| 476 | nav_platform | Linux aarch64 |
| 479 | nav_platform | Linux i686 on x86_64 |
| 480 | nav_platform | Linux ppc64 |
+-----+--------------+--------------------------------------+
"masking-agent" is a browser privacy extension that changes the platform by default to that.
The weird long one is a Sony Z10
browscap.ini? The project has been rebooted earlier this year. – Robbert