Marek Kotewicz ("debris")
DEVCON0 self-introduction
Marek Kotewicz was a core developer on Ethereum's C++ team who built the JavaScript API (web3.js) and JSON-RPC layer. He was based in the Berlin office and left with Gavin Wood to co-found Ethcore (Parity).
JavaScript API and Web3.js
Marek worked on unifying the JavaScript front-end across Ethereum's C++ and Go clients. Gavin Wood described his work in ÐΞV Update II:
"Marek has studiously been moving C++ over to a JSON-RPC and Javascript front-end fundamentally unified and bound to the Go client."
At DEVCON0 in November 2014, Marek presented the JavaScript API in a workshop setting, explaining how it worked with smart contracts and what tools would be available for developers.
Fabian Vogelsteller, who became the first heavy user of web3.js while building the Mist browser, worked closely with Marek in the Berlin office:
"I had to get into web3.js, which Marek was working on… I was literally the first user of that library and really contributed to that library as well." — Fabian Vogelsteller (Episode 12)
Departure to Ethcore
When Gavin Wood left the Ethereum Foundation, Marek was one of the core developers who joined him. Gavin wrote in his farewell post:
"Together with core developers Arkadiy and Marek and a troupe of others, I'll be working to make The Dream a reality as part of a sparkly new venture."
After Marek's departure, Fabian Vogelsteller took over maintenance of web3.js.
Primary Sources
This profile draws from:
- Gav's ÐΞV Updates through V
- The Last Blog Post (Gavin Wood's farewell)
- DEVCON0 Recap
- Episode 12 with Fabian Vogelsteller
Back-links
Other pages that reference this:
- Stiftung Ethereum (Articles, July 14, 2014)
- Gav's ÐΞV Update I: Where Ethereum's at (Articles, October 17, 2014)
- DEVCON0 (Articles, November 24, 2014)
- From inside Ethereum ÐΞVhub Berlin (Articles, December 02, 2014)
- ÐΞVcon-0 Recap (Articles, December 05, 2014)
- Gav's Ethereum ÐΞV Update V (Articles, March 02, 2015)
- The end of the beginning… (Articles, May 02, 2015)
- Another Ethereum ÐΞV Update (Articles, June 15, 2015)
- The last Blog Post (Articles, January 11, 2016)
- A Brief History of Digix (More pictures than words) (Articles, March 07, 2016)
- Early Days of Ethereum - Episode 12 - Fabian Vogelsteller (Videos, February 25, 2026)
- Ethcore (Articles)
- Mist (Articles)
- Fabian Vogelsteller (People)
- Gavin Wood (People)