Fintech Full-Stack Engineer — Scale & Modernize

ClassWallet; United States; On-site; USD 120,000 - 180,000; Full time

Benefits offered by this job

Excellent salary and benefits commens.

Job summary

ClassWallet, a leading fintech in the United States, is hiring a Full Stack Engineer to modernize a large fintech platform. You will contribute to a mature Node.js/Express+MongoDB backend and a multi-generation frontend, building NestJS services and Next.js UI, writing tests, and delivering scalable solutions within a rigid legacy system.

Join a team that values judgment, disciplined refactoring, and careful migration.

Qualifications

• 4+ years shipping production full-stack
• Strong TypeScript front and back
• Experience with NestJS (or Express/Fastify w/ DI)
• Experience with Next.js/React (hooks, App Router, SSR/CSR)
• Experience with PostgreSQL or MySQL (schema, indexing, migrations)
• Ability to design scalable solutions within a rigid legacy system
• Testing discipline (Jest, Playwright/Cypress, Supertest)
• API design (REST, auth, backward-compatible evolution)

Responsibilities

• Work across the full stack — data model, API contract, UI, and production behavior.
• Recognize and replace bad legacy patterns; apply better practices in new development.
• Design for scale while integrating with a rigid legacy system.
• Build on the modern stack: NestJS modules and Next.js apps.
• Understand strangler-fig approach and contribute without downtime.
• Move transactional data from documents to normalized SQL with proper constraints.
• Write tests as a default: unit, integration, E2E.
• Identify and raise test gaps, N+1 issues, and index improvements.

Skills

Full-stack development

TypeScript

API design

Testing discipline

Tools

NestJS

Next.js

React

PostgreSQL

MySQL

RabbitMQ

Jest

Playwright

Cypress

Supertest

AWS

Docker

Kubernetes

Job description

ClassWallet, a leading fintech in the United States, is hiring a Full Stack Engineer to modernize a large fintech platform. You will contribute to a mature Node.js/Express+MongoDB backend and a multi-generation frontend, building NestJS services and Next.js UI, writing tests, and delivering scalable solutions within a rigid legacy system.

Join a team that values judgment, disciplined refactoring, and careful migration.