Marissa Posner is a developer, data scientist, and entrepreneur with experience across the Web3, data science, and finance industries. She currently serves as a Product and Developer Relations contributor on the Ethereum Foundation’s Account & Chain Abstraction team. Throughout her career, Posner has co-founded several ventures, including ChainBrain, Sugarcane, and Gold. ^[1]​

Career

Early Career & Other Ventures

Her career began with an internship in the U.S. Senate office of Senator John F. Kerry from 2012 to 2013, where she worked with Senate staff on environmental policy, drafted memos, and attended hearings. From 2015 to 2019, Posner was a professional fencer, competing internationally as a member of the Israeli National Fencing Team. During this period, she also explored her interests in technology and entrepreneurship. In 2017, she was selected as one of 55 participants for Google’s BOLD Immersion program in Mountain View, California. The program provided her with exposure to international marketing strategy as she shadowed product managers for YouTube, Android Pay, and Cross-Product Strategy. Concurrently, from 2017 to 2018, she founded and operated Sweat Addicts, a fitness community where she managed brand development, content creation, partnerships, and fundraising. This venture generated over $1,000 in revenue from events and included digital content collaborations with brands such as Lynx Active and Emily Hsu Designs. ^[1]​

Teampay (2019–2022)

Transitioning into a dedicated data science role, Posner worked at Teampay from 2019 to 2022. As a Data Scientist, she was responsible for the company's analytics infrastructure, fraud detection systems, pipeline optimization, and financial forecasting. In prose, her key achievements included building a vendor-matching model with third-party integration, designing an event-driven fraud detection system, and improving payment revenue forecasting accuracy by over 4x using ARIMA models. She also developed a scalable entity-resolution pipeline and created PostgreSQL analytics databases. Her work involved a tech stack comprising Python, PostgreSQL, Django, AWS, FastText, Linux, and custom ETL workflows. ^[1]​

ChainBrain (2023)

In 2023, she co-founded and served as the Chief Executive Officer of ChainBrain, a Web3 analytics platform designed to simplify the process of searching, visualizing, and interpreting blockchain data, where she led product strategy, data tooling development, and early user growth. ^[1]​

Sugarcane (2023–2024)

From 2023 to 2024, she co-founded Sugarcane, a social-centric DeFi investment platform, and served as its Chief Technology Officer. At Sugarcane, she oversaw platform architecture, product design, and team execution for the platform, which allowed users to collaborate on investment strategies and share portfolios. ^[1]​

Gold (2024–2025)

From 2024 to 2025, Posner co-founded Gold, a social gaming platform for on-chain games, acting as its Chief Technology Officer. In this role, she led the product architecture, infrastructure design, and the launch of the space-farming strategy game, Skyoneer (formerly CropXYZ). Under her technical leadership, the company saw the successful sale of $400,000 in in-game digital assets for Skyoneer and deployed the first Layer-3 blockchain on Base, which processed hundreds of thousands of transactions. ^[1]​

Ethereum Foundation (2025–Present)

Since January 2025, Posner has served as a Product and Developer Relations contributor on the Ethereum Foundation’s Account & Chain Abstraction team. In this role, she focuses on enhancing the developer experience and product direction for account abstraction and multi-chain UX initiatives. ^[1]​