Open to opportunities

Nicolas Fainstein

@nicolasfainstein

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I build typed full-stack products, SDKs, and developer APIs with TypeScript, React, and Node.js.

Argentina

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What I'm looking for

I'm looking to lead and build production full-stack products, typed APIs, SDKs, and developer platforms with TypeScript, React, and Node.js.

At Wonderland, I led three engineers on the cross-chain module of the open-source Interop SDK built with the Ethereum Foundation. I remained the top committer while owning a partner-facing TypeScript API, release process, audit response, and GitHub Actions automation.

Previously, as one of six people at Balmy, I rebuilt the frontend architecture for a full product rebrand and built a yield aggregator across three external protocols. I also worked on Node.js and Express transaction-history APIs, caching and pagination, and a React Native mobile app with biometric authentication.

I've also led a JavaScript-to-TypeScript migration at La Nación, built Storybook libraries and role-based login flows at Apeel Sciences, and delivered an online learning platform used by 50,000+ students worldwide.

Experience

Work history, roles, and key accomplishments

Technical Lead

Wonderland

Apr 2025 - Jul 2026 (1 year 3 months)

Led three engineers on the cross-chain module of the Interop SDK built with the Ethereum Foundation. Owned the module's TypeScript API, release process, and CI automation, and represented the team in technical sessions with external partners.

TypeScript React Next.js SDK GitHub Actions CI CD Testing Jest Cypress Playwright

Founding Full-Stack Developer

Balmy

Sep 2023 - Apr 2025 (1 year 7 months)

Owned the frontend architecture rebuild behind a full product rebrand, including a codebase rewrite, service layer, Storybook component library, and test coverage. Built a yield aggregator end to end and worked on the transaction-history API.

TypeScript React Next.js Express React Native Expo Storybook Testing Jest Cypress Playwright

Frontend Developer

La Nación

Sep 2022 - Sep 2023 (1 year)

Led the JavaScript-to-TypeScript migration on a high-traffic sports site and trained the team on it. Built the site from scratch and centralized third-party API calls and transformations behind an integration layer.

TypeScript JavaScript React API Integration

Frontend Developer

Apeel Sciences

Jul 2021 - Sep 2022 (1 year 2 months)

Implemented a login flow with role-based permissions and moved the frontend application to a hosted deployment. Built and maintained a Storybook component library.

React Storybook Authentication Role Based Access Control Deployment

Tech Product Analyst

IMS Internet Media Services

Jan 2020 - Jul 2021 (1 year 6 months)

Built the front end for an online course platform that reached 50,000+ students worldwide, including custom e-learning components. Rebuilt the site on WordPress and integrated it with marketing and analytics tools, and owned the project roadmap and backlog.

WordPress Integromat HubSpot Mailchimp Google Analytics Power BI Frontend Development E Learning

Programming Tutor / Teacher

Coderhouse

Jan 2020 - Dec 2020 (11 months)

Taught web development fundamentals to students and mentored beginners day to day. Graded weekly assignments and ran support sessions.

HTML CSS Git Teaching Mentor

Programming Tutor / Teacher

Ministry of Education

Jan 2020 - Dec 2020 (11 months)

Taught web development fundamentals to public high-school students in the Aprende Programando program. Graded weekly assignments and mentored beginners.

HTML CSS Git Teaching Mentor