(2018 version)

Monday, January 22, 2018

We build in 2018 to raise awareness about the inefficient use of block space by exchanges, services, and wallets. The project is a joint effort with Bitrefill CEO @ziggamon.

In early 2018 the price of bitcoin surged to 20.000 USD. At that time we saw more than 400.000 daily transactions on the Bitcoin network which caused a steep increase in transaction fees. A lot of exchanges, services and wallets did not use the block space efficiently. We build to raise community awareness.

Header and input field for the old site
input field of the 2018 version site

Only a few exchanges and services made use of payment batching or spend SegWit outputs in 2018. This meant, for example, that every withdrawal was costly for exchanges as the withdrawal transaction takes up a lot of space in the blockchain. Often the transaction fees or even a higher fixed fee was deducted from the user’s withdrawal amount. Our site allowed users to check the fee efficiency of their transactions and their wallets. It calculated how much fees could have been saved by using, for example, payment batching or by spending SegWit outputs. Green checkmarks for fee- and space-saving behavior and red crosses for inefficient and wasteful behavior.

WayBackMachine: 26th August 2018

Later, we added a subsection with charts about payment and feerate metrics to the site. We offered all data under a CC0 “No Rights Reserved” license. The website has appeared in numerous online news articles since then, one, for example, being Bitcoin’s median transaction fee lowest since 2011 — nearing BCH. The data even made its way into academia.

Due to low usage of the fee efficiency checker over 2019 and us reaching our goal to raise awareness we decided to overhaul the site and released a second iteration in 2020.

Read more about the 2020 version
All text and images in this work are licensed under a Creative Commons Attribution-ShareAlike 4.0 International License Creative Commons License


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June 23, 2018

Konstantin Nick (@sputn1ck) and I build for the Lighting Hackday in June 2018. You could play Pokémon via the Lightning Network build. Pressing the buttons of the GameBoy to move the player and to interact with the world would generate a lightning invoice. Paying that invoice would send the pressed button to the game-backend and the user could see the action over the live stream. The site not longer up, but parts of it can still be seen on


Image for (2017 version)

October 7, 2017 (2017 version)

The website displays statistics about my Bitcoin mempool. This covers the 2017 version which I iterated on in 2019.