Blockchain-powered Christmas trees are proving popular this year. Two separate teams of developers, one at the University of Ljubljana in Slovenia and the other funded by Nano, introduced interactive trees this month, with lights that can be changed via a blockchain donation.  

The projects are real world examples of how physical things can be manipulated via a simple blockchain interface. They demonstrate the technology’s power alongside smart meters and the Internet of Things (IoT), and are designed to encourage understanding and adoption.

The Ethereum Christmas tree

The Ethereum powered tree resides in the lobby of the University of Ljubljana’s Faculty of Electrical Engineering.


“It’s a working prototype the students can use,” the project’s leader Matevž Pustišek told Decrypt

“We provided a simple web user interface. You can open it on your mobile phone or another device, and then you can select the colour of the lights and the period [of time] the lights should go on for. In the background, it executes an Ethereum transaction which is accepted by a smart contract,” he said.

The smart contract is composed by a device dubbed Swether, an IoT gadget designed by the team to manage the lights. In essence, Swether intercepts events from the Ethereum network and toggles its state accordingly. Anyone with the link to access the site can control the tree. But, since the team has yet to install a webcam, there’s no way to see the result unless you’re in the lobby. The donations are currently supplied by the Faculty.

Nevertheless, Pustišek considers that it’s a good starting point for students to develop decentralized applications such as charging points for mobiles and electric cars, or applications for the smart grid.

The Nano Christmas tree

Ethereum Christmas
Nano's Christmas tree at the Pixel Bar in Leeds, UK. Image: Vimeo.

Log on to the live stream for e-sports venue Pixel Bar in Leeds, UK, and you can see its very own Nano powered Christmas tree.


To change the lights on the tree, you can send Nano donations using a QR code via a simple interface. The last digit of the sum sent dictates what the lights will do—there are ten different program patterns to try out.

The project is a collaboration between the Nano Center, which funds the blockchain’s initiatives, and the Pixel Bar. Funds will be donated to Simon on the Streets, a charity which helps the homeless of Leeds get back on their feet. 

“We developed this to show that you could have a fun and engaging way to drive donations for charity by having something cool and innovative tied to a simple donation,” one of the developers on the project posted on Wednesday, on Reddit. “We’ve raised approximately £500 for Simon on the Streets, and hopefully delivered some holiday cheer along the way as well.”

What’s most remarkable about the project is the speed of its transactions. Nano combines blockchain technology with a Directed Acrylic Graph (DAG), a structure which sees individual transactions directly linked to one another rather than grouped for processing in blocks.

According to Nano, when dedicated Nano wallet Natrium is used for the transaction, the tree lights change in as little as 170 milliseconds. There’s a demo here.  

And in answer to the Redditor who asked: “Can’t someone just unplug it and plug straight into the wall outlet?

It’s about adoption, you klutz. Next stop: Times Square.

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