Full-Stack, Backend Leaning, SWE

Job summary

Own the backend architecture, including APIs, data models, and business logic to ensure product scalability and reliability. Collaborate with product and design teams to build full-stack features and translate ambiguous user needs into maintainable implementations.

Job details

About This Role There is an enormous gap between the technology built in Silicon Valley and what the average small business owner in America can actually get their hands on. The pharmacist in rural Louisiana. The auto dealer in the Midwest. The vet clinic owner who has done their books the same way for twenty years. They run the businesses that hold American communities together, and the software serving them has never reflected how much they matter. Affiniti is closing that gap. We're building the financial operating system for small businesses across America, and the frontend is the bridge. Every dashboard you ship, every interaction you refine, every millisecond you shave off a load time is technology finally reaching the people who needed it most and never got it. If you want to write code that matters beyond the product itself, this is that opportunity. Location NYC (in office), Canada (remote) Tech Stack TypeScript, Node.js, and React Key Responsibilities Own the backend architecture behind our product. APIs, data models, business logic, and the foundational decisions that determine how the product scales, performs, and stays reliable. Drop into the full stack when it counts. Build frontend flows, wire up React components, and trace a bug from the browser to the database without waiting on anyone. Build the systems that power complex financial products. The kind of backend where messy financial data, integrations, and business logic become simple, reliable experiences for customers. Obsess over the details that separate software that works from software customers can trust: data integrity, API latency, failure modes, query performance, and the edge cases most engineers skip. Partner closely with product and design to push past the requirements. Challenge assumptions, propose better solutions, and make sure what we build solves the actual customer problem — not just the technical specification. Turn ambiguous user needs into clean, maintainable implementations. And advocate for the user in every technical decision. What You’ll Bring 2+ years of production engineering experience. Early-stage startup experience strongly preferred. Deep fluency in TypeScript and Node.js, with real opinions about API design, data modeling, backend architecture, and system reliability. End-to-end ownership and strong product instincts. You can take a feature from idea to shipped without a frontend engineer holding your hand, and you care as much about the customer experience as the systems underneath it. You know how to build with AI, not just use it. Tools like Claude Code, Codex, and other coding agents are a core part of your engineering workflow, and you know how to use them to dramatically increase your speed and output without outsourcing technical judgment. A track record building complex, data-rich products backed by systems operating under real reliability and performance constraints. Speed without the debt. You move fast without leaving behind the kind of backend mess that makes a codebase painful six months later. High ownership. You take problems as your own and see them through — the mark of the people who thrive here. Work Authorization Candidates must be currently authorized to work in their respective country. For this role, we are considering U.S. candidates who are U.S. citizens, U.S. lawful permanent residents (Green Card holders), or individuals who otherwise currently hold valid authorization to work in the United States. For Canadian candidates, we are considering Canadian citizens, Canadian permanent residents, or individuals who otherwise currently hold valid authorization to work in Canada. Equal Opportunity Employment Affiniti is an equal opportunity employer. We are committed to building a diverse and inclusive workplace and consider all qualified applicants for employment without regard to race, color, religion, sex, pregnancy, national origin, age, disability, genetic information, veteran status, sexual orientation, gender identity or expression, or any other characteristic protected by applicable federal, state, or local law. Affiniti provides reasonable accommodations to qualified individuals with disabilities and applicants with disabilities throughout the recruiting process, consistent with applicable law.

What you’ll do

Own the backend architecture, including APIs, data models, and business logic to ensure product scalability and reliability. Collaborate with product and design teams to build full-stack features and translate ambiguous user needs into maintainable implementations.

Requirements

Requires at least 2 years of production engineering experience with deep fluency in TypeScript and Node.js. Candidates must possess strong product instincts and the ability to manage end-to-end feature development independently.

Benefits

• Equity
• Reimbursed relocation
• Free lunch
• Free dinner
• Paid technology equipment set up
• Health insurance
• Dental insurance
• Vision insurance

Listed skills

• TypeScript · Preferred
• Node.js · Preferred
• React · Preferred
• Product Development · Preferred

Other relevant skills

Identified from the job description. Confirm important requirements above.

• Typescript
• Node.js
• React
• Backend architecture
• API design
• Data modeling
• System reliability
• Full-stack development
• Data integrity
• Query performance
• API latency
• Software engineering
• Product development
• AI tools
• Financial Operating Systems
• Claude Code
• Full Stack Development
• Workplace Inclusivity
• Workflow Management
• Advocacy
• Query Performance
• Application Programming Interface (API)
• Artificial Intelligence
• Business Logic
• Customer Service
• Data Integrity
• Data Modeling
• Failure Causes
• Financial Services
• Financial Data
• Front End Design
• Node.js (Javascript Library)
• Outsourcing
• Production Engineering
• Technology Assessment
• TypeScript
• Authorization (Computing)
• Reliability
• Load Time
• React.js (Javascript Library)
• Codebase
• API Design

Job areas

• Software
• Engineering
• Technology
• Finance & Accounting
• Back End Software Engineer
• Back End Developer / Engineer
• Web and Multimedia Developers
• Web Developers

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