Senior Full-Stack Engineer (Node.js / TypeScript)

OnHires; Miami (FL); On-site; USD 120,000 - 180,000; Full time

Job summary

OnHires is partnering with a fintech startup reimagining cross-border money movement. You will join as one of two founding engineers, owning features end-to-end across backend services and the application layer.

You'll work closely with the founders to design scalable APIs, ship fast, and shape engineering culture while building a product already used in 130+ countries. This early-stage team offers broad ownership and a clear impact path.

Qualifications

• 5+ years of professional software engineering experience.
• Strong full-stack development across backend and frontend.
• Proficiency in JavaScript and TypeScript.
• Experience building production applications with Node.js.
• Product mindset and passion for high-quality UX.
• Thrives in fast-moving startup with high ownership.

Responsibilities

• Own and deliver features across the entire stack.
• Design and build scalable APIs and backend systems.
• Collaborate with founders, product, and design to ship features.
• Make architectural decisions balancing speed, scalability, and maintainability.
• Improve product quality, reliability, and user experience.
• Debug complex technical challenges across multiple layers of the stack.

Skills

5+ years

Full-stack

JavaScript/TypeScript

Node.js

Product mindset

Startup ownership

Tools

React

AWS

Kubernetes

Terraform

Web3/Blockchain

Job description

About Our Client

One of our clients is reimagining how money moves around the world.

They're building a global fintech platform that combines the simplicity of a modern banking app with the power of blockchain technology—without exposing users to the complexity of crypto. The goal is simple: make sending, spending, and managing money across borders feel effortless.

Already serving thousands of users in 130+ countries, the company is now accelerating growth after recently raising $5M in seed funding from leading US and European investors.

This is an early-stage company with a lean, high-caliber engineering team where every line of code has a visible impact on the product.

About the Role

This is one of two founding engineering hires and a unique opportunity for a product‑minded full‑stack engineer who enjoys owning features from end to end.

You'll build across the entire stack—from backend services and APIs to the application layer—working directly with the founders to bring ideas to life. The engineering team believes in shared ownership, so you'll have the freedom to contribute wherever you can create the biggest impact.

If you enjoy solving challenging technical problems while building products users genuinely love, you'll fit right in.

What You'll Be Building

• Own and deliver features across the entire stack—from backend services to frontend experiences.

• Design and build scalable APIs and backend systems using Node.js and TypeScript.

• Collaborate closely with founders, product, and design to turn ideas into shipped features.

• Make architectural decisions that balance speed, scalability, and maintainability.

• Improve product quality, reliability, and user experience across the platform.

• Debug complex technical challenges across multiple layers of the stack.

What We’re Looking For

• 5+ years of professional software engineering experience.

• Strong full‑stack development experience across backend and frontend.

• Deep expertise in JavaScript and TypeScript.

• Solid experience building production applications with Node.js.

• A product mindset and a passion for building high‑quality user experiences.

• Comfortable thriving in a fast‑moving startup environment with high ownership.

Nice to Have

• React and/or React Native.

• AWS, Kubernetes, or Terraform.

• Consumer product or fintech experience.

• Blockchain, Web3, EVM, or Solidity experience (nice to have, not required).

• Early‑stage startup experience.

• Experience helping establish engineering culture and technical standards.

Why You’ll Love This Opportunity

• Join as one of the company's first founding engineers

• Build a global product already used in 130+ countries

• Work directly with the founders and have a real voice in technical decisions

• Ship fast with minimal bureaucracy and see your work in production quickly

• Help shape the engineering culture, architecture, and future of the platform

• Own features from idea to launch—not just individual tasks

• Join a well‑funded startup with $5M in seed funding and years of runway

• Make an outsized impact while the team is still small

Who Thrives Here?

We're looking for builders who love ownership, move fast, and enjoy creating products from the ground up.

The strongest candidates are product‑minded engineers who care about the user experience just as much as writing great code. Startup experience is highly valued, but curiosity, initiative, and a willingness to learn matter even more.