Wear OS
The card is
already on
your wrist.
Star a card on your phone and it appears on the watch. Not a notification, not a remote view of the phone: a real app with a real tile, holding its own copy, so it opens with the phone in your bag, in another room, or flat on the kitchen table.
One swipe from the watch face, hold it out, done. The phone stays where it is.
Not on Google Play yet
CardJar is built and tested and is going through the last checks before the Play listing opens: Android and Wear OS first, iPhone and Apple Watch after. One message, when there is something to install, and nothing else ever.
How it works
Four things the watch app does, and one it refuses to do.
A tile, not a shortcut
The card you used last sits in a Wear OS tile in your own colour. One swipe from the watch face and it is on screen.
Its own copy
Favourites are stored on the watch itself, so it works with the phone out of range entirely. Nothing is fetched at the moment you need it.
It hears the phone
Star a card on the phone and the tile changes without you opening the watch app first. The phone publishes; the watch listens.
Only favourites travel
Not your whole jar. Only the cards you star, and only the fields the watch draws: no notes, no timestamps, no archived cards.
The refusal
It tells you when a watch screen is the wrong place for a card.
A striped 1D barcode drawn 40 millimetres wide is a hard target for a supermarket laser, and pretending otherwise fails at the worst possible moment.
So when a card uses a 1D format, the watch says “Might not scan here”, and underneath it: “Watch screens are narrow, so laser tills often miss it. Your phone will be fine.” Once per card, not every time, with a Show it anyway button below, because sometimes the till has an imaging scanner and it works perfectly.
QR, Aztec and Data Matrix are a different story: two-dimensional codes are read by a camera rather than a laser line, and they do well on a small bright screen.
The phone-to-watch link goes one way, over a connection the two already have.
Favourites travel from your phone to your watch over the link a paired phone and watch already maintain with each other. Nothing about it reaches us, and nothing is added to what the two devices already exchange to be paired at all.
The watch keeps card numbers in its own private storage, in the same position as the phone. A watch is more often unlocked than a phone is, and that is worth knowing: if a particular card is not one you want on your wrist, do not star it. Only favourites are ever sent.
Questions about the watch
Which watches does it run on?
Wear OS. The watch app is delivered from the same Play listing as the phone app, so installing on the watch is the usual one tap once the phone app is on.
Does it work with my phone out of range?
Yes. The watch holds its own copy of your favourites, so the app and the tile open and draw with no phone nearby at all.
What about Apple Watch?
Planned, alongside the iPhone app. Both watch platforms are meant to be first-class surfaces rather than afterthoughts, which is why the Wear OS app is a real app rather than a notification.
Will a supermarket scanner read my watch?
For QR, Aztec and Data Matrix, usually yes. For striped 1D codes such as EAN-13, often not, because a laser scanner needs a wider target than a watch can give it. CardJar tells you which case you are in before you are standing at the till.
Can I get my whole jar on the watch?
No, by design. Only starred cards travel, which keeps the watch fast and keeps the cards you did not choose to put on your wrist off it.
A loyalty card you have to dig your phone out for is a loyalty card you stop using.
Not on Google Play yet
CardJar is built and tested and is going through the last checks before the Play listing opens: Android and Wear OS first, iPhone and Apple Watch after. One message, when there is something to install, and nothing else ever.