Full Stack Engineer

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 financial technology company in the United States serving agencies delegated responsibility to manage public funds, is seeking to hire a Full Stack Engineer to join our team.

Agencies use ClassWallet to get public funds to the right people, and ensure the funds are used for the right purpose. ClassWallet's suite of products and services empowers agency administrators to dramatically increase efficiency of funds distribution and spend compliance, reduce programmatic costs, maximize the full potential impact of the program, and satisfy the needs and expectations of policymakers, constituents and public reporting. ClassWallet has processed over $6.7 Billion to date and serves public agencies across 39 states. In its 11+ years in operation, ClassWallet has completed over 12M transactions, funded 1.1M recipients, processed over 5M applications, and now serves 300+ state and local agency clients, supported by a team of 280+ full-time staff.

The Company has developed an industry-defining digital wallet solution which has gained rapid traction among state and local agencies and school districts across America. ClassWallet ranks as the 61st fastest growing software company on the prestigious Inc. 5000 list of fastest-growing private companies and the 21st fastest growing financial technology company on the Deloitte Technology Fast 500 in 2023.

While the Company delivers immense business value, the social impact of ClassWallet is a fabric that runs through its mission and corporate culture. As a result of ClassWallet’s innovation, public programs run with exponentially more efficiency and the impact and breadth of the programs for the individuals they serve is dramatically higher. This mission compliments the Company mission-based culture with focus on gratitude and work-life balance.

About the Role

We're modernizing a large, business-critical fintech platform. Our current system is a mature Node.js/Express + MongoDB backend (with RabbitMQ workers, batch jobs, and a reports service) paired with a tri-generational frontend — layers of Backbone/Marionette, legacy React class components, and a React + Redux + Material-UI app all coexisting in one codebase.

We're looking for someone with the judgment to tell good patterns from bad ones — who can recognize where the legacy system went wrong, avoid repeating those mistakes in new work, and design scalable solutions that still have to live alongside a rigid, established system. You'll contribute to new NestJS services and Next.js UI, write tests, and ship changes that respect the constraints around you — using AI tooling (Claude Code, Copilot) as a force multiplier, not a crutch.

What you'll do

• Work across the full stack — data model, API contract, UI, and production behavior — contributing to domains as they move onto the modern stack.
• Recognize bad legacy patterns and don't repeat them — read the existing Express/MongoDB and Backbone/React layers, understand where they fell short, and apply better practices in new development rather than carrying old habits forward.
• Design for scale within real constraints — build solutions that scale even when they have to integrate with a rigid legacy system that can't be changed wholesale.
• Build on the modern stack — NestJS modules (DI, guards, interceptors) and Next.js apps (App Router, server components, typed clients).
• Understand the strangler-fig approach — how legacy and new run side by side, behind feature flags, with zero data loss and no downtime — and contribute to it without disrupting it.
• Model relational data carefully — help move money-bearing/transactional data from documents into a normalized SQL schema with real constraints and safe migrations.
• Write tests as a default — unit, integration, E2E. The suite is what lets the team move fast safely.
• Spot and flag problems — the flaky test, the N+1, the missing index. Raise them clearly so they get prioritized, and pick them up when it makes sense.
• Use AI tooling efficiently while understanding and standing behind every line that lands.

• 4+ years shipping production full-stack
• Strong TypeScript front and back
• NestJS (or deep Express/Fastify w/ DI grasp)
• Next.js/React (hooks, App Router, SSR/CSR)
• PostgreSQL or MySQL (schema, indexing, transactions, migrations)
• An eye for distinguishing good patterns from bad legacy ones
• Ability to design scalable solutions that fit within an existing, rigid system
• Testing discipline (Jest, Playwright/Cypress, Supertest)
• API design (REST, auth, backward-compatible evolution)

Bonus

• Experience migrating off a legacy code
• Fintech/payments/ledger
• Message queues (RabbitMQ/SQS/Kafka)
• MongoDB/Mongoose Aggregation
• AWS/Docker/Kubernetes/CI
• Deliberate AI-agent use in production workflows

Who you are

• Takes ownership and responsibility for their work
• Eager to take initiative and grow
• Has the judgment to spot bad legacy code and the discipline to not repeat it in new work
• Designs for scale even inside rigid constraints
• Refactors and builds with better practices rather than carrying old patterns forward
• Moves carefully without breaking trust (tests + small PRs + flags)
• Communicates trade-offs clearly
• Raises issues and flags risks rather than routing around them

Our stack

• Today: Node · Express · MongoDB · RabbitMQ · React/Redux · Backbone · Material-UI · AWS · Jest
• Going: NestJS · Next.js · TypeScript end-to-end · PostgreSQL/MySQL · full automated coverage

ClassWallet is a positive, family-oriented team environment. Our focus is on encouragement, positive reinforcement, and gratitude. We work hard and are highly motivated to win but with a healthy perspective on life.

We offer an excellent salary and benefits commensurate with experience.

ClassWallet.com is proud to be an Equal Opportunity Employer. Applicants are considered for all positions without regard to race, color, religion, sex, national origin, age, disability, sexual orientation, marital or veteran status.