Activate NFC at Any Time
One of the biggest gripes we have with our NFC-enabled devices is the somewhat unnecessary requirement of having to unlock them in order to activate NFC. This requirement effectively reduces the practicality of our many enabled stickers, tags, and gadgets, as it leads to another inconvenient step that limits the use of NFC in the first place.
There is good news, though, as a couple of good folks here have created mods that allows for NFC activation when the device’s screen is off or at the lock screen. This has been made possible by XDA Senior Member StephanSch for the following devices:
This mod is also available for the Samsung Galaxy S4 thanks to XDA Senior Member OptimalKiller. The mods come in some variation of a modified NFC APK that is then moved to the /system/apps directory, thus requiring root access. It’s important to note that the mods are compatible with only certain specific builds, frameworks, and devices. Because of this, you have to make sure to download and install the correct version. Also, make some sort of backup to ensure that you can revert the effects if things go awry.
For more information and detailed instructions, visit the threads for the following devices: HTC One, One X, EVO 4G LTE, Sony Xperia Z, Xperia P, Xperia Sola, Samsung Galaxy S2 Skyrocket, and Galaxy S4.