Senior Fullstack Engineer – Social, Desktop & Applications

About River

River is the human layer of the internet. The consent and ownership infrastructure that puts people back in the loop. Users see their data, control who accesses it, earn 70% of the value it creates, and get AI that finally serves them, not the platform.

We are pre-revenue, raising a $3M seed at a $30M pre-money, and preparing for market launch. Our founding CEO brought MTV and NetJets to Europe and we are backed by technology luminaries from Google, Sun Microsystems, and beyond.

We are looking for a Senior Fullstack Engineer to build the products that put individual intelligence in users' hands – from our live social platform to our desktop AI client and beyond. This is a foundational hire that will underpin our expanding team. You will be the person who shapes the user-facing experience across River's product suite, building beautiful, performant applications that people actually want to use.

What We're Building

River is three products, one platform:

• River Social – live and growing. A social platform where you own your data, control your identity, and get paid when it's used. 70% of value goes back to you.

• River Source – enterprise consent infrastructure. The bridge that gives AI platforms and brands access to high-fidelity, consented user data at scale.

• RiverAI – launching 2026. A desktop AI client built on your personal data graph, with real agentic capabilities that work for you, not just talk to you.

What You'll Be Doing

• Building and evolving River Social – developing new features, refining the user experience, and scaling the frontend and supporting services of River's live social platform.

• Developing desktop application UIs – building polished, responsive interfaces for RiverAI's desktop client, bridging web technologies with native desktop capabilities to deliver a seamless user experience.

• Shipping applications – contributing to the design and development of standalone apps across River's product suite, from concept through to production release.

• Working across the full stack – while your strength is in frontend and application development, you'll build and maintain the backend services, APIs, and data layers that support the features you ship. You understand what's happening behind the API and can contribute meaningfully to it.

• Implementing new features end to end – taking ownership of features from design handoff through frontend implementation, backend wiring, testing, and deployment.

• Optimizing performance and user experience – ensuring fast load times, smooth interactions, and high availability across web and desktop surfaces.

• Maintaining code quality and engineering standards – writing clean, well-tested code, participating in code reviews, and contributing to CI/CD and testing best practices as the team grows.

• Collaborating closely with product and design – translating product vision and design specifications into working software, and pushing back constructively when technical constraints require creative solutions.

What We're Looking For

BS/MS in Computer Science, Software Engineering, or equivalent practical experience.

5+ years of experience in professional software development, with demonstrated expertise in the following:

• Strong proficiency in TypeScript and JavaScript (ES6+).

• Extensive experience with React and modern frontend development – building polished, responsive, component-driven user interfaces.

• Solid experience with Node.js and Node.js-based frameworks (Express, Fastify, NestJS).

• Understanding of RESTful APIs and microservices architecture – you can build and maintain backend services, not just consume them.

• Experience with both SQL and NoSQL databases (PostgreSQL, DynamoDB, MongoDB) and a practical understanding of data modeling.

• Experience with event-driven architectures and message queues (Kafka) is a plus.

• Familiarity with cloud services and infrastructure (AWS preferred).

• Strong problem-solving skills and attention to detail.

• Experience building applications – you've shipped desktop, mobile, or standalone apps (Electron, Tauri, React Native, or similar), not just web pages. You understand the unique challenges of building software that lives on a user's device, including local storage, system integration, and offline capability.

Above all, you must have:

• A startup mentality – you thrive in fast-paced environments with ambiguous requirements, can move fluidly between frontend polish and backend plumbing, and are energized (not daunted) by building something from scratch.

• Full ownership mindset – you take features from idea to production. You don't stop at the frontend boundary; if something needs to work end to end, you make it work end to end.

• Strong communication skills and the ability to work closely with product, design, and backend engineers to ship cohesive products.

• A passion for ethical technology and data sovereignty principles, sharing our vision that AI should empower users, not exploit them.

Nice to have:

• Experience with mobile app development – React Native, Swift/SwiftUI, or Kotlin/Jetpack Compose.

• Familiarity with mobile-specific concerns: app store submission and review processes, push notifications, deep linking, and platform-specific design patterns (iOS HIG, Material Design).

• Experience with cross-platform development strategies – sharing code and components across web, desktop, and mobile surfaces.

• Experience with desktop application frameworks (Electron, Tauri).

• Experience with CSS animation, motion design, or rich interactive UI development.

• Experience building complex data visualizations – interactive charts, graphs, dashboards, or novel visual representations of data (D3.js, Victory, Recharts, or similar).

Why You Should Join River

Most engineering jobs are maintenance work on someone else's idea. This isn't that.

The core technology is built, the patents filed, and the partnerships in place. The work ahead is the work that matters: taking what we've proven into the hands of real users, at scale, and building the company around it. You will ship things that millions of people will use.

The team blends operator experience, engineering depth, and startup hustle. You get significant equity, real ownership of what you build, a direct line to the founders, and the rare chance to work on problems no one has solved yet.

The market is ready. Join us.

How to Apply

Email [email protected]

This role is remote. Applicants must be currently authorized to work in the United States and will be required to provide evidence of their right to work as part of the hiring process. Standard business hours are based on the Pacific Time Zone and availability during these hours is essential. References will be sought for shortlisted candidates.