Tap-to-pay with CashuBTC ecash — for bitcoin.
Fiat credit cards nailed the UX: fast, offline, works anywhere.
I always wanted that for Bitcoin.
Now it’s open-source. Private. Instant. Beep, done.
In the video: two Cashu wallets for bitcoin.
Left:
@Minibits (PoS)
Right: cashu.me (payer)
Ecash is sent directly via NFC — no internet, no delay. Beep, boop.
Ecash is a bearer token — the money lives on your device, not on a server. That’s why it pairs so well with NFC. Pick an amount, tap to send. No talking to servers. No syncing. Just push it over. The payment is pretty much instant. A PoS can accept ecash from any mint and receive payments via Lightning.
Still early days, but we’re experimenting. Card-to-phone works, but phone-to-phone? That’s the real killer use case.
Apple famously locks down the iPhone’s NFC chip — good monopolist.
F*k that. I found a workaround.
As long as one phone (ideally the PoS) is Android, you can send data both ways between iPhone and Android.
(You don’t really own your iPhone.)
Peace!
Replies (58)
Fucking legend.
Very interesting - sparked my interested in ecash. Apparently the EU are forcing Apple to open NFC up? That and USB-C is about the only good thing the EU have done :-)
This is so amazing!
I'm imagining shop owners would want to have mini it's autosweep to their lightning nodes after the "register" had over 500 in ecash or something.
Ditching iPhone is on my todo list.
Amazing btw!
Mine too.
Sick!!!
Get on that!
Woow!
orange nuts magic 🍊⚡️🥜
You can use it if you're a corpo fintech or bank and have apple's permission
Ah … is that all they unlocked? :-(
You’re teaching me some cool things!
Calle I want to learn more about using ecash offline. Can you point me in the right direction to some resources?
reat work, cypherpunks write code ✊🗽
cool, but couldn't the payer reverse the payment when connecting back to the mint first?
🔥
Yet another historic 0 to 1 leap.
View quoted note →Noice ✊🏻 I can’t wait to get an opportunity to try it out
It's possible to lock ecash to a pubkey and add signature proofs, to solve this problem. The sender would need to get the pubkey from the receiver first though, which is worse UX.
Receiver can also just redeem after tap, and finalize the transaction after redemption
Some slides on that topic. I am releasing offline tokens feature to nutstash.app this weekend! I plan on writing a short blog about it. Stay tuned!
Do you do this all on your own? If so, why doesn't it exists already 10 years?
P2P payment through NFC
🤯
calle
Tap-to-pay with CashuBTC ecash — for bitcoin.
Fiat credit cards nailed the UX: fast, offline, works anywhere.
I always wanted that for Bitcoin.
Now it’s open-source. Private. Instant. Beep, done.
In the video: two Cashu wallets for bitcoin.
Left:
@Minibits (PoS)
Right: cashu.me (payer)
Ecash is sent directly via NFC — no internet, no delay. Beep, boop.
Ecash is a bearer token — the money lives on your device, not on a server. That’s why it pairs so well with NFC. Pick an amount, tap to send. No talking to servers. No syncing. Just push it over. The payment is pretty much instant. A PoS can accept ecash from any mint and receive payments via Lightning.
Still early days, but we’re experimenting. Card-to-phone works, but phone-to-phone? That’s the real killer use case.
Apple famously locks down the iPhone’s NFC chip — good monopolist.
F*k that. I found a workaround.
As long as one phone (ideally the PoS) is Android, you can send data both ways between iPhone and Android.
(You don’t really own your iPhone.)
Peace!
If we can use p2pk locks with ecash when both sender and receiver are offline... that would be ground breaking!
So I am very eager to know more. Currently I can't do it on chasu.me, but I assume there's a technical limitation that I don't fully understand yet. So want to understand more.
Bitcoin person to person payments.
That easy…
Theres just no reason to have PNC, Bank of America, JP Morgan, Blackrock, US Gov’t, Chinese Gov’t, Paypal, Venmo, or any of those companies to take our money and pay somebody FOR US and take a cut EVERY FUCKING TIME when there ways now that we can just do it ourselves 🤷♂️
My wife and I just paid a tree service yesterday, and they charged us over $50 for literally no reason other than to cover the costs of Visa.
Meanwhile if that company had just accepted Bitcoin payments, the transaction would’ve cost $0.03 🙄
Just feel like i’m getting tired of waiting for everyone to figure out how to help themselves and help society. Its like people only ever complain about money, but don’t take the time to look at it and see what exactly it is they hate, and how to change the shit they hate!
🤙
Beauty!
thelimitations:
I have it fully implemented in nutstash, will release it on the weekend
gandlaf21
It's possible to lock ecash to a pubkey and add signature proofs, to solve this problem. The sender would need to get the pubkey from the receiver first though, which is worse UX.
Receiver can also just redeem after tap, and finalize the transaction after redemption
Any idea why my tokens are stuck in pending mint for days? Was playing around with cashu.me. Deposited 10 sats on Lightning, tried to mint tokens (or at least I think I did) and it’s been like this for days.
is there any significance to the fact that in one direction there was no fee, but in the other direction there was a fee?
you probably sent some ecash, but whoever you sent it to never claimed it. Go to "history" click on your ecash and copy it. Then you can receive it to your wallet.
Thank you. Really appreciate that. It worked. Need to play around with it more and get used to it.
>You don’t really own your iPhone.
What about with GrapheneOS?
we need to figure out this UX.... maybe we need the "cancel transaction" button after all.
I think a simple reclaim on the sent ecash
Reclaim button.
Wow! It’s like a peer-to-peer electronic cash system! 🤯
moar buttons!
lnbc7770n1pnams47pp54d5gzkpeqzfw6qcfvvyf0y69e9t999804w827rd60kf04j8xv9nqdp5wdshgueqvehhygrwv4shgcn0vf3kzap3xfq8qunfd4skctnwv46qcqzzsxqrrs0sp5eymemgn28aytmug8vkjrrk3u7kd43mk2ej0fyhakq4tshqkdzw9s9qxpqysgqj08hex0605e9mv0wujgeuuw2tgk40mpvemyx6c423pwkdxa3644nwypujjcmvfrnmy4qa4kjdfs58rh9ygkp9c9gkazpenccqdzch3gpqn0624
Hero
When I think of cashu.me, my core vibrates with excitement, like when bitcoin finally clicked in the middle of the night.
I find myself thinking of setting up a small business in my local area selling something below cost, but only if it is payable in btc, just to spread the understanding.
npub12rv5lskctqxxs2c8rf2zlzc7xx3qpvzs3w4etgemauy9thegr43sf485vg is an artist, a renaissance man, and is laying down an important plank in the foundation of a future world of abundance ...
Thank you npub12rv5lskctqxxs2c8rf2zlzc7xx3qpvzs3w4etgemauy9thegr43sf485vg ...
nevent1qvzqqqqqqypzq5xeflpdskqvdq4swxj59793uvdzqzc9pzatjk3nhmcg2h0js8trqyt8wumn8ghj7etyv4hzumn0wd68ytnvv9hxgtcpzemhxue69uhks6tnwshxummnw3ezumrpdejz7qpqsmm5ulx6gptuhv9627kx72zyx494ha6sdqjv8mwrcmdkm8mrkq4s4mfm3u
nevent1qvzqqqqqqypzq5pswp0cfu82uwwnjvvrruyd9d55xkdzvn3zksvlragjk3fy6j8lqythwumn8ghj7un9d3shjtnwdaehgu3wvfskuep0qy28wumn8ghj76mpv3shyem09ea8wtnfwvhsqgqevu7myzk3vw8k59ld6fvltr3p5t6lr3yftvlz0wxtxy2ywqy54szgajkz
It made my morning 😇🤞🍇
View quoted note →Interesting! I used to think Cashus were a waste of time and effort because of the inherent rug risk. Now I think it is useful as PoC for the future when Arc tech matures. I can see myself holding a bearer Bitcoin that can be unilaterally exited to chain in a worst case scenario.
That's for Google Pixel
No. The receiver considers the transaction "settled" if he can swap the ecash for new one. If it's already spent, the Mint will error.
vinney...axkl
I hope that in retrospect, the single best use-case for nostr ends up being that it collectively figured out new ways to fund protocols rather than products.
Watching a gif of
@calle sending ecash over NFC between phones... I can imagine building a rich and beautiful world on top of open protocols like ecash, lightning, bitcoin and nostr. I cannot imagine building a world worth living in top of Venmo and Twitter. I won't fucking contribute to that.
I will go down on this ship - and I actually currently am. My knees are wet. Pls send help.
I know. I have GrapheneOS
I'm old and just now saw the 'i', I thought it just said 'phone'
ffs
This is freaking awesome. The UX/UI improvements of this are massive. Question regarding offline payments, I don't see a way of guaranteeing no double spend.
Are you taking the approach that trust between customer/provider is required in this scenario? IMO, that's a total valid point. The service provider would swap the tokens as soon as it can to guarantee full ownership, right?
we are on the right track to a sovereign and decentralized future
Calle…. my G! You be heavy!
Sender needs no Internet, receiver needs it!
so the receiver must be online and talk to server
Yes in this case. If the tokens are p2pk locked and with proof of issuance then the receiver doesn't need to be.
Were u at tab7conf?
Wink one for yes, twice for no
a SOLID steppingstone for adoption⚡️⚡️⚡️
View quoted note →Long live Bitcoin!
View quoted note →
