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Ethan

Founding Engineer

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Ethan Blumenthal
Available for Coffee

Hi, I'm Ethan

Full stack product engineer - always shipping

Driving Bitcoin adoption by building revolutionary FinTech and PropTech products. 7 years of experience engineering with emerging technologies.

Frontend
Backend
DevOps
AI Agents
Crypto

Featured Projects

Commercial real estate technology solutions at scale

Castle preview
Active

Castle

Bitcoin SMB Treasuries

2025-Present
Founding Engineer

Castle is on a mission to help businesses save. We believe fixing the money is of critical importance. With sound money like bitcoin we can finally enable hard-working businesses to save again. We're grateful to help build that future. Castle automates your bitcoin treasury with integrations to keep everything in sync. Link your payment or bookkeeping platform to keep allocations right-sized to your business. Built with purpose: simplify your operations, save your time, fortify your capital.

B2B
Early Stage
Miami, FL
Flow AI preview
Active

Flow AI

Agentic CRE Workflows

2024-2025
Co-Founder, CTO

Flow AI is revolutionizing commercial real estate with its agentic workforce. Designed to streamline the formulaic yet human-dependent processes of private equity firms, Flow replaces investor relations and financial modeling teams by answering complex queries, analyzing deal data, and enabling a unique "Vibe Modeling" experience. Flow AI addresses inefficiencies in a historically opaque market, reducing costs, closing times, and errors while unlocking untapped data potential.

B2B
Early Stage
Austin, TX
Cityfunds preview
Active

Cityfunds

Home Equity Originations

2023-2024
VP of Engineering

Nada is an award-winning fintech and investment platform on a mission to unlock the wealth trapped within the $30 trillion home equity market for homeowners and investors. As the first company qualified by the SEC to issue city-specific shares of home equity, Nada’s Cityfunds product provides investors with direct access to the home equity market. By investing in the equity of homes, Nada is providing homeowners with immediate liquidity without the burden of added debt or monthly payments. Nada's innovative platform aligns individual investors with homeowners to build and preserve their wealth through the power of home equity.

B2C
Growth Stage
Austin, TX
OwnProp preview
Active

OwnProp

Tokenized CRE Investments

2021-2023
Founding Engineer

OwnProp is democratizing access to commercial real estate investing, enabling new economic opportunities for all to a once inaccessible market. Real estate yields the highest and most stable returns of any asset class, yet has previously only been available to the wealthy due to high minimums, low liquidity, and a significant knowledge gap. OwnProp is solving these problems by using blockchain technology to reduce overhead costs, increase transparency, and speed up the settlement of transactions. OwnProp’s tokenized investment opportunities include iconic properties that provide predictable appreciation as well as cash flow. The OwnProp platform is currently available to accredited investors as we work towards opening up to retail investors in summer of 2023.

B2C
Early Stage
Austin, TX