NFC

Near-field communication (NFC) can be used for contactless exchange of data over short distances. Different approaches exist on Linux to support it:
* libnfc: userspace implementation, but mostly for desktop (e.g. USB) readers
* Android NFC HAL: doesn't really work outside Android, probably mostly proprietary implementations
* Linux NFC subsystem: NFC abstraction in the (mainline) Linux kernel with support for many different (also embedded) NFC chips
* sailfishos/nfcd appears to implement neard dbus API, as well as providing card emulation
For smartphones/embedded devices the Linux NFC subsystem is the most suitable one, because it can be set up normally in the device tree like other hardware. Unfortunately, the NFC subsystem has been somewhat unmaintained for quite some time, and especially the userspace portion of it: Neard.
Note that there is support for NFC/Neard in Qt if you want to build an application that makes use of NFC yourself.
== Devices with NFC support ==
If your device runs the mainline kernel, and has a NFC chip that is supported in mainline's Linux NFC subsystem it should be fairly easy to add it to the device tree. Check the available NFC device tree bindings for details. Otherwise, these devices in postmarketOS already support NFC to some extent:
== Applications that require NFC to work properly==
Application name 	Toolkit	License 	Short Description 	Note
AusweisApp 	Qt 	EUPL-1.2 	Official eID client in Germany for EU eIDAS 	🚩 This app needs to be installed from a third-party Flatpak repository. de.bund.ausweisapp.ausweisapp2
eSzemélyi Kliens 	Qt 	Proprietary	Official eID client in Hungary 	🚩 This app is x86 & x86_64 only and needs to be installed from a third-party site and currently is only in .deb and .rpm packages.
Thales (formerly Gemalto) SConnect 	- 	Proprietary	Browser Plug-In for official Swedish and Belgian eID web applications	🚩 This app is x86 & x86_64 only and needs to be installed from a third-party site and currently is only in tar.gz package.
Digital identity and trust infrastructure (Switzerland)	- 	MIT 	Official Swiss eID pilot program 	🚩 This is still a pilot program, and at the moment this requires Waydroid, but the law mandates open source and so far more or less everything is on GitHub, so there is hope for improvements.
== Applications that can use NFC, but NFC is not strictly required ==
Application name 	Toolkit	License 	Short Description 	Note
Yubico Authenticator	Flutter	Apache-2.0	Open source authenticator app for Yubico's own hardware security products.	🚩 NFC support for Linux is in Yubico/libfido2 and is still considered experimental. This app needs to be installed from a third-party Flatpak repository. com.yubico.yubioath
== Testing ==
As a basic test, you can use nfctool (from apk add neard) to poll for devices:
$ nfctool -d nfc0 -1 -p
nfc0:
 Tags: [ ]
 Devices: [ ]
 Protocols: [ Felica MIFARE Jewel ISO-DEP ISO-15693 ]
 Powered: Yes
 RF Mode: None
 lto: 0
 rw: 0
 miux: 0
Start polling on nfc0 as initiator
Targets found for nfc0
 Tags: [ tag0 ]
 Devices: [ ]
If you hold some other NFC-capable device close to the NFC antenna, it should find a NFC tag and show it. Many chip cards nowadays have NFC, or maybe you can use another smartphone.
=== Reading NFC tags ===
For advanced usage you should start the Neard daemon (rc-service neard start). Neard then provides a DBUS API similar to BlueZ for Bluetooth that allows reading/writing NFC tags for example.
The easiest way to test it is using the Neard test scripts, for example with test-adapter and test-tag.
Upstream is looking for potential maintainers and testers of the Linux NFC subsystem, so if you would like to help, consider posting on the linux-nfc mailing list.
== See also ==
* Testing wanted for Linux NFC subsystem
Category:Guide