Can a locked NFC tag be unlocked?
No. There is no tool, no application, no phone, no service and no manufacturer procedure that reverses it. The lock bits are designed to move in one direction only, so there is no command to undo and nothing for anyone to reverse.
The answer, without qualification
No.
Not with a different application, not with a better phone, not with a dedicated reader, not by contacting the chip manufacturer, and not with any of the tools that appear in search results claiming otherwise.
This page exists because the question is asked constantly, usually by someone who has just locked a batch, and because the internet contains a great deal of hopeful misinformation about it.
Why it is genuinely impossible
Locking is not a setting stored somewhere that could be changed back. It is a set of bits that the chip's own logic refuses to clear, at the hardware level, with no command in its instruction set that would do so.
A manufacturer cannot help because there is nothing to help with. They did not withhold an unlock command, they built a chip that has none. Asking is not unreasonable and the answer will always be the same.
Nor is there a physical workaround. Reaching the memory cells directly would require destroying the chip, at a cost that is absurd next to a tag worth a few cents.
What people ask instead
Three follow up questions come up every time, and all three have short answers.
Can I format it? No, because formatting is a write and the memory refuses writes.
Can I erase it? No, for the same reason. The content stays exactly as it was at the moment of locking.
Can I at least change what it points to? Only if the tag holds a redirect address you control, in which case you change the destination at your server and the tag never needs touching. That is precisely why writing a redirect makes locking safe.
What to actually do
If the tag is loose, discard it and use another. A tag costs cents and an hour of attempts costs more than a hundred tags.
If the tag is already applied to something and removal is the expensive part, check whether its content is still usable. A locked tag holding a working link is not a problem, it is a finished tag.
If the content is wrong and the tag is installed, the remaining options are to place a second tag beside it, or to remove and replace it. There is no third option, and no amount of searching will produce one.
Frequently asked questions
Are the tools claiming to unlock tags real?
No. Some reset content on unlocked tags and describe it as unlocking, which is a different operation entirely. None can clear lock bits, because no such command exists.
Will the manufacturer unlock it if I ask?
No, and not because they refuse. The chip has no unlock command, so there is nothing for them to run.
What if only part of the tag is locked?
The unlocked region remains writable and the locked one does not. If your content fits in what is left, the tag is still usable.
Can I recover the tag by putting it in a strong field?
No. Lock bits are stored electrically like any other data and are protected by the chip logic. No field strength, magnet or reader changes that.