Ecash was invented in the year 1982. That's 41 years ago!!! But why have you never heard of it until in recent years? Well, this article pretty much explains it.
Ecash has basically been dead for the past decades, but it is seeing a revival now. Why?
The answer is Bitcoin.
Bitcoin offers the perfect foundation for building ecash application on top. And this time, it can happen in a free market, where there is no longer a company gate keeping the patents for ecash.
A lot of time has passed since the inception and downfall of ecash. People are now used to holding balances at banks, holding UTXO private keys, swiping credit cards, having liquidity in lightning channels.... But this old new thing called "ecash" seems foreign.
We as developers and creators of user interfaces also struggle with this. Understanding ecash from a technical perspective helps to grasp what might be going on behind a user interface, but how can we design this so using an ecash wallet feels intuitive?

The ecash is stored in the wallet, on YOUR device

You might have heard the term "ecash token". But what is a "token"? It's an often misused term, and the whole shitcoin-token stuff made things even more complicated. Shitcoins are not tokens. They are UTXOs, but on a crappy chain.
The correct way to describe a token would be a casino chip. It was issued by someone (in this instance the casino) and has some value ascribed to it. You can bring the chip back to the issuer and get back its ascribed value.
Ecash works the same way, but in addition we use cryptography to break traceablilty links while giving the issuer the means to prevent double spending. We have to do this, because data is easy to forge and copy, while the same thing would be hard with casino chips.
So when using ecash, you are litterally holding the tokens inside your wallet:
Each peice of data that is a token represents some cash value. In the case of cashu, it represents satoshis on the lightning network, redeemable at the issuer/mint of the token. (yes you heard right, ecash is fully custodial, so always keep that in mind when using ecash)

Send or pay? Redeem, receive or topup?

Take a look at this:
pretty overwhelming right? What's the difference between pay and send? Am I trying to confuse the user?
Maybe a little. But the truth is, there is not much to pull from. Ecash is still in its UX baby shoes, and there is much left to explore. Last week we spent some time exploring ideas on how to simplify the user experience.
The first step, is to have less buttons on the main screen. The user either want's to increase or decrease the wallet balance. So we only give him the options to send or receive.
In the next step, for example if the user wants to receive sats into the wallet, ha can make the choice wether to use Lightning or Ecash:
Similarly for sending, we would see something like this. Again the user can choose to create a token to send, or scan a lightning invoice:
There is much more to show, but maybe it's too much for going into all the details. but anyway here is a screenshot for a sneak peek has been working on:
We appreciate all the feedback, please join the nutstash telegram group and let us know what you think:
And if you made it this far, try to redeem this: