NFC Tags
Stick an NFC tag on a water bottle, a snack box or the fridge, and tap your phone on it to log a drink, a food or a saved meal, without opening the app and finding the right button. You set up each tag once; after that, one tap logs it.
NFC tags are in the mobile app only (iPhone and Android). The web app does not manage tags.
What a tag can log
Tags log water and drinks, a food or a saved meal. Medication and exercise are planned, and a tag you set up now keeps working when they arrive.
What you need
- A phone with NFC. Almost every recent iPhone (XS and later for tapping with the app closed) and Android phone has it.
- Blank, rewritable NFC tags or stickers, usually sold as NTAG213. They cost a few cents each.
- On-metal tags for steel bottles. Ordinary stickers usually fail on metal, so a steel tumbler needs a tag sold as "on-metal" or "anti-metal".
- A SparkyFitness mobile app and server that both include NFC tags. Update your server first; an older server shows "Your server does not support NFC tags yet".
- You must be signed in to your server in the app.
Set up a tag
Open what you want to log and tap Add NFC tag:
- a water container (Library, then Water containers),
- a food (Library, then Foods),
- a saved meal (Library, then Meals).
You can also go to Settings, then NFC tags, tap + and choose Water or drink or Food or meal.
Choose what one tap logs, and name the tag:
- Water or drink: the container and how many drinks.
- Food or meal: tap the row to open the same search you use for logging, with your foods and saved meals together, online results and barcode scan. Pick the item and set the amount on the same screen as when you log it: a serving or grams of a food, or servings of a meal (grams for a meal measured by weight). You can change the amount later on the tag.
For a food or a meal, choose where it goes under Log to: By time of day (the default) picks the meal that matches the time of the tap, using each meal type's usual time, as quick logging does. You can also pick one meal type, for example Snacks for a tag on a snack drawer.
Save, then hold your phone to the tag when asked.
The amount is saved with the tag, so a tap never asks for it. To log a different amount, change the tag or log that time by hand. A meal tag logs the saved meal as it is in your Meals library, so editing the meal's ingredients changes what its tags log.
If the tag already holds something else, such as a link or a card, the app asks before replacing it.
You can change what a tag does later, in the same screens, without touching the tag. To move a tag to a new sticker, open it and use Write to a tag again.
Use a tag
Unlock your phone and hold it to the tag. The app does not need to be open.
| Phone | What happens |
|---|---|
| iPhone (XS or later) | A banner appears. Tap it, and SparkyFitness opens and logs. |
| Android 15 and older | SparkyFitness opens and logs. |
| Android 16 and later | SparkyFitness opens and logs, or Android shows a notification to tap first. Android 16 may also ask once whether the app may open from NFC. |
A message such as Logged 1 × Stanley or Logged 170 g Greek yogurt appears with Tap to undo. Undo removes exactly the drink, food or meal that tap logged.
If tapping does nothing, open Settings, then NFC tags and use Scan a tag, then hold the phone to the tag.
Good to know
- Accidental taps: turn on Ask before logging for a tag to get a Log or Cancel prompt on every tap.
- Double taps: a second tap within about 10 seconds is ignored, so holding the phone on the tag too long logs only one drink.
- Deleted container, food or meal: if you delete what a tag logs, the tap tells you and logs nothing. Open the tag and pick something else. Entries the tag logged before stay in your diary, unless you delete a food together with its history.
- Deleted meal type: if a tag always logs to a meal type you later delete, it logs by time of day instead.
- Someone else's tag: a tag that is not set up on your account logs nothing. The app offers to set it up for you.
- Offline: if your server cannot be reached, the app says so and logs nothing. Tap again when you are back online.
- Several people: each person sets up their own tags, so two people can use the same bottle, each logging to their own account.
- Removing a tag: open it and choose Remove this tag. The sticker keeps its link, but a tap on it no longer logs.
Privacy
A tag holds only a web link with a random code, https://tag.sparkyfitness.com/t/<code>. It holds no health data, and what the code does is stored on your own server. The tag site stores nothing and is used only so your phone knows the link belongs to the SparkyFitness app. Without the app installed, the link opens a page that tells you to install it.
Limits
- A tag logs to the server the app is signed in to. If you switch servers, a tag from the other server reads as unknown.
- Tapping with the app closed works in the App Store and Google Play versions. Development builds, and builds made from source with a different app ID, use Scan a tag instead.
- An APK from GitHub releases opens from a tap on Android, but is not updated by Google Play.