Down an alley just outside the WIRED offices in San Francisco, Darwin Cafe is one of those coffee shops that gleefully resists technology. The place runs on an old-fashioned register, with big keys that thunk and a drawer that ka-chings. Jack Dorsey would get itchy just walking inside.

On Friday afternoon, I ordered an iced latte and a Green Tea White Chip Whoopie Cookie, and handed over my credit card for the $7.95 bill. (Darwin's technology may be anachronistic, but its coffee prices are very much with the times.) The barista swiped my card, and then looked at it, perplexed, turning it over in her hands.

Shit. It didn't work. Of course this crazy one-card-for-all-your-cards idea is bad. Technology is stupid. I hope I have my wallet. "Did it not go through?" I asked. "Was there an error message?" "Oh no," she said, handing the green and gray card back to me. "It worked. It's just a really nice card. What is it?"

It's Stratos. It's a single card designed to replace all your credit, debit, loyalty, and membership cards with one piece of plastic. It works with a smartphone app to store and switch between cards, and activates with a single tap. It lights up, you press on the plastic once to pick your card, and it swipes. It's easy, and it's going to confuse everyone.

Tap, Swipe

There are a thousand upsides to a card like Stratos, even beyond finally ditching your gigantic George Costanza wallet. It can make sure you actually use your gift cards, or make getting a loyalty card totally automatic. It's much more secure than a standard credit card, for a variety of reasons. If you lose it, just shut it off—you don't need to cancel the individual cards themselves. It even uses Bluetooth to warn you if you left it in the check-holder, and will shut off if you get too far away.

There are also a thousand cards like this, whether it's Stratos, Coin, Plastc, Wocket, Swyp, or a (probably-doomed) Kickstarter project of your choosing. Stratos's big advantage is that it looks just like a super-stylish credit card, which is more impressive than it sounds: Most of Stratos's competitors are big, ugly, or both. Stratos feels like a fancyman's credit card, like it belongs to someone who always gets upgraded on flights or has a guy he can call when he needs something done discreetly.

My card arrived in an enormous bamboo box, which contained a Moleskine notebook, the card, and a smaller box with the card reader inside. The setup process is elegant and simple: Stratos's Android or iOS app holds your hand as you attach the card reader and scan in your cards (which takes a few tries). You can have as many as you want stored in the app, but only three active on the card at once.

Right now, all you can really do is dump all your cards in Stratos and go shopping. So I did both. In the name of thoroughness and testing and all that is good about gadget journalism, I bought all the crap I could carry.

I found the card works anywhere your normal credit card does, as long as you know the trick: You have to whack it on the table, the reader, or your palm right before you use it. The only way for the Stratos to last two years is for it not to be on all the time, so the tap activates it: A tiny LED blinks next to the active card, and it's ready. (Double-tapping connects it to your phone.)

This is fine when you're using it yourself. It becomes a tic, even—part of the routine of swiping and signing. But go ahead and try handing your credit card to a waiter or bartender and saying, "you just have to tap it once before you swipe it, you'll see the light, and then it'll be fine." It won’t be fine.

I tried explaining as much to a very confused, very tired server Friday night. Her response was to ask me where the hidden camera was. After some convincing, she came back a few minutes later with my check. Turns out if you're willing to explain how Stratos works every time you hand it to a cashier, bartender, or waiter, it works every time. Still, I was embarrassed enough that I switched back to my regular credit card when we went to the bar. And I tipped the doubting waitress about 40 percent.

It's a little awkward, this card. It's an amazing ad for itself, because you can't use it without talking to somebody about how it works or why it exists. And the basic promise is true: Stratos can replace every card that looks like it. In many cases, though, it took three or four or nine tries to get the card to read. It doesn’t feel like living in the future when you're swearing at the Walgreen's register while the line builds behind you.

Part of the Stratos appeal is that it looks like a high-end credit card. Stratos

A Better, Better Credit Card

With Stratos's annual subscription, you're paying $95 a year (or $145 for two) for a credit card that doesn't give you points or miles, just a modicum of convenience and some cool-card swagger. Yet Stratos CEO Thiago Olson is convinced this thing will pay for itself. This is where things get interesting: The Stratos app is learning how to think about your money and rewards for you. The app will remind you, whenever you're at the gas station, that one of your cards offers double points on gas. Booking a Delta flight? You’re prompted to use your Delta AmEx, dummy. The company is also working on tokenized identity, meaning it's not transmitting your card number every time you swipe, and will give you burner card numbers for one-time purchases. Little of this works now, but there's a long and impressive roadmap.

Stratos is working with retailers and banks to make it easy to sign up for and use loyalty and membership cards, and they're even considering co-branded cards. The next time you get a Chase Visa, it may well come with Stratos tech inside. Olson uses the word "platform" a lot, as in: Stratos is a platform for aggregating your cards and figuring out how you can use them best. The one-card-to-rule-them-all thing is just the beginning.

It's not really true, either. In my weekend with Stratos, I also used my work keyfob, an NFC-enabled train card, and a paper bus pass. I needed my driver's license, and my health insurance ID. And I went to two cash-only places. Stratos can't replace your wallet. It can just make it a little thinner.

Your subscription buys you upgrades, though: You'll get a new card once a year, Olson says, with new tech and new features. Next on Stratos's radar is NFC and chip-and-pin payments, so you'll be able to tap your credit card on a reader and pay even faster. That'll make the payment process easier, and help Stratos replace a lot of cards it currently can't touch. Fingerprint authentication is coming, too, which would turn Stratos into an Apple Pay alternative that doesn't require your phone. Buy now, Stratos promises, and you'll get upgraded forever.

The big question, though, is how many upgrades until we don't need a card anymore? Sure, some retailers don't yet support NFC, and sure, it's awkward to hand someone my phone (or my watch) so they can head behind the bar to run my card. But I have to imagine we're more likely to solve that problem than to simply continue to improve upon swipeable credit cards. Many restaurants already bring the bill to you, and whole businesses are run on iPads. Hell, Chili's has a "Ziosk" right on your table so you can pay your bill whenever you so desire. Chili's!

This first Stratos card isn't the final product. Olson says it's just a way to get into the market, to show customers and potential partners what a card like this can do. The story's much bigger than slimming your wallet: It's about making paying for things easier, more efficient, and more customer-friendly. Even if it does confuse a few bartenders in the process.