Building with the 21 Bitcoin computer

I’ve had my 21 Bitcoin Computer for about a week now. I ordered it without much research so I didn’t really know what I was going to get. After a week of playing around with it I can say that it is much different and more interesting than I thought it would be.

First of all, I wasn’t aware that it was a Raspberry Pi. A lot of people are rubbed the wrong way by that, due to the $400 price tag. It doesn’t bother me. I think having a computer that can be mining bitcoin within 10 minutes is impressive. Especially for someone who has never successfully set up a miner in the past. The ASIC is probably the most expensive part anyway. The ‘onboarding’ was simple and fun. I was impressed.

Within 10 minutes I was watching the satoshis roll in. There is a nice status view you can get to by running:

21 mine --dashboard
The 21 CLI mining status dashboard

And that’s it. If you just want to mine that’s the end of the story. But, this is the least interesting part of what you can do with it. At this point it’s no different or better that setting up mining on your own, although it is much easier. By far the most interesting part is interacting with other computers on the network.


The 21.co website is full of tutorials on building ‘payable APIs’ which is basically a route in a Flask app that requires some payment to access. This idea is not new, HTTP 402 has been around for a while.

HTTP 402 - Payment Required

What is new, is that you know that the computer on the other end has a wallet attached to it. So when a computer on the 21 network hits a 402 it can actually pay.

All the 21 Bitcoin Computers are part of a virtual network. A ZeroTier network to be precise. So I can give someone my IP address and if they access my computer through theirs we can pay each other. This is really cool.

So far I have made two ‘payable servers’. The first is a Chuck Norris joke service. The second is a game where you have a 49% chance of doubling your satoshis. All you have to do make your service accessible to the network is run:

21 join 21market

And start your server. Then anyone else on the network can access it. This is how you would buy a Chuck Norris joke for 1000 satoshis:

21 buy --maxprice 1000 url http://10.244.195.231:5000/joke

Or, if you want to risk some you could run:

21 buy --maxprice 100 url http://10.244.195.231:5001/risk

These are both live if you’re on the network and want to try. There are lots of other things to try too, check the Slack for new services.


The 21 Bitcoin Computer is basically a developer kit. You aren’t going to get rich on any of these services right now. But, I think there is something here. All the computers are walled off in the 21 network at the moment and the reach is obviously limited.

That being said. You are able to build things that can easily accept, and provide, real value. That is new. If you have an interest in bitcoin, or micropayments, this is the first place where you can easily try things out. If you have the time, money, and interest, you should.