The problem

You have heard these at your front desk.

Who was in the building when the fire alarm went?

Facilities manager

We print new cards every time somebody leaves.

HR and administration

The visitor book is a paper book.

Reception

None of these is a card problem. A card is a few rupees of plastic. The hard part is twenty phones agreeing what a card means today, and a history nobody can quietly rewrite.

How it works

Tap. The server decides. It is recorded.

1

Tap

Somebody holds a card to a phone at the door, the desk or the machine. Any NFC card works, including the one they already carry.

2

The server decides

The console knows whose card it is today, whether the pass has expired, and what should happen. Change it once there and every phone follows.

3

Recorded and announced

The tap lands in the ledger with the card, the phone and the time. An arrival can be spoken aloud on the phone or on an Echo.

Two kinds of card

One card can be recognised or written.

This is the difference between TapKit and a tag-writing app. Most deployments use both.

	Recognised (UID mode)	Written (NDEF mode)
How it works	TapKit recognises the chip's id. The server decides what it means.	The data is written onto the card itself.
Which cards	Any chip, including locked hotel, transit and office cards	A writable tag: NTAG213, 215 or 216, a few rupees each
The phone needs	TapKit, joined to your workspace	Nothing. Any Android phone or iPhone
Change what it does	From the console, instantly. Same plastic, new meaning	Rewrite the card in person
If it is lost	Revoke it centrally, in one step	Cannot be revoked. Seal it so nobody can rewrite it
Recorded	Every tap, in the ledger	Only when the card points at your server (UID and counter mirroring)
Use it for	Staff, students, visitor passes, assets	Guest Wi-Fi, wall signs, anything handed to the public

A tag-writing app can write a Wi-Fi card. It cannot re-issue yesterday's visitor pass to today's visitor, revoke a lost card from a desk, or tell you who was on site at 3pm. That is what TapKit is for.

By industry

Find your building.

Each page walks through one real day with TapKit in that kind of place.

What is in the box

Built, and proven on real cards.

Everything listed here works today. Tap any item to see what it does.

Nothing matches that. Try a shorter word.

Web console

Cards, phones, routines, the ledger, people and roles, an audit log, and CSV export.

Visitor passes

Book, arrive, sign out. A pass stops working on its own when it expires.

Spoken announcements

On the phone, or on an Echo through a bridge. Ask Alexa who is on site and it answers from live data.

Proof

The details we got right.

Each of these was found by testing with real cards and a real reception desk, not on a whiteboard.

Bluetooth pairing that actually pairs

The Bluetooth specification wants the device address byte-reversed. Written the way it reads on the label, pairing silently fails. TapKit also writes the device class, so a phone knows it has paired with a speaker and moves the music to it.

// example address
Label    00:11:22:AA:BB:CC
On card  CC BB AA 22 11 00
Class    04 04 24  headset

A replay is not a second visit

With no signal, a phone queues its taps and sends them later. Each tap carries an id the phone made, so a replay is ignored rather than counted twice, and nobody is announced twice.

Tap	Ledger	Spoken
Live pass, first	yes	arrival
Replay of a sent tap	no copy	no
Pass expired	yes	no
Unregistered chip	yes	no

The 90-second settling window

In the first live test, a visitor tapped, did not hear anything, tapped again and was signed out seconds after arriving. Now a second tap within 90 seconds repeats the welcome instead. After that, it signs them out.

09:41:02  tap  arrived, announced
09:41:09  tap  within 90s: welcome again
10:52:40  tap  signed out

Offline first, by design. When the internet is down, taps queue on the phone and replay when it is back, without double counting. A card wired straight to a relay or a local Home Assistant keeps working with no internet at all.

Questions

The straight answers.

Does it work with Alexa?

Yes, through a bridge. An Alexa skill cannot push an announcement to an Echo on its own, so TapKit speaks through Voice Monkey or Home Assistant, which you set once in the console. Separately, the TapKit Alexa skill answers "who is on site" from live data.

Does it work on iPhone?

Written cards do, with nothing installed. Recognised (UID-mode) cards need the TapKit app on the reading phone, and there is no iPhone app yet, so the phones at your doors and desks should be Android. Visitors and staff can carry any phone.

Can we use the ID cards we already have?

Usually, yes. Locked cards such as hotel keys, transit cards and most office ID cards cannot be written, but they work in UID mode, which reads only the chip's id and never changes the card.

Is a card secure enough to open a door?

Not on its own, and we will not tell you otherwise. A chip id can be copied with an inexpensive reader, and card passwords travel over the air in clear: they stop casual tampering, they are not security. For a door that matters, put Require unlock (fingerprint, face or PIN) above the action, or pair the card with a camera.

What happens when the internet goes down?

Taps queue on the phone and replay when the connection returns. Each tap carries its own id, so nothing is counted twice. Actions wired directly to a relay or a local Home Assistant keep working with no internet at all.

What if a phone is lost?

Revoke that one phone from the console. Every phone has its own key, so nobody else has to re-join, and console sign-ins are a separate system that a lost phone cannot touch.

Why not use a free NFC app?

The free tag apps are good at writing tags, and if one card for your own phone is all you need, use one. The difference is the console, the shared registry and the ledger: what a building needs once more than a few people tap more than a few cards.

What hardware do we need?

Android phones with NFC, and NFC cards. NTAG213 cards and stickers cost a few rupees each; a card on metal needs an on-metal tag. We can supply cards printed with your design and encoded before they arrive.

Where is our data kept?

Used on its own, the app keeps everything on the phone. Joined to a workspace, taps go to that workspace's ledger on servers run by Archana Info Solutions. The app asks only for NFC, internet and vibrate: no camera, location, contacts or storage.

Watch a tap do something.

Thirty minutes, real cards, your questions. We set up a workspace that looks like your building and walk a visitor through it.

Book a demo Get the app

Already using TapKit? Sign in to the console

The same card means something different tomorrow.