Backend Engineer: Scalable FinTech APIs & Data

Affiniti; New York (NY); Hybrid; USD 150,000 - 240,000; Full time

Benefits offered by this job

Relocation assistance

Free meals in NYC

Tech setup provided

Health, dental, and vision insurance

Job summary

Affiniti is building the financial operating system for small businesses across America, with the frontend as the bridge. We’re hiring engineers in NYC in-office hybrid with relocation support.

You will own the backend architecture, APIs, data models, and the reliability foundations that scale our product. You’ll also collaborate across product and design to turn ambiguous needs into clean, maintainable systems, sometimes touching frontend as needed.

Qualifications

• 2+ years of production engineering experience in an early-stage startup or similar environment.
• Strong expertise in TypeScript and Node.js, with opinions on API design and data modeling.
• Demonstrated ability to own features from idea to production with focus on reliability and performance.

Responsibilities

• Own the backend architecture behind our product: APIs, data models, and core logic to scale and stay reliable.
• Drop into frontend flow when needed: build React components and trace issues from browser to database.
• Build systems for complex financial products with data-rich integrations and robust error handling.
• Focus on data integrity, API latency, failure modes, and performance edge cases.
• Collaborate with product and design to translate user needs into solid technical solutions.
• Advocate for users in technical decisions, turning ambiguous needs into clean implementations.

Skills

TypeScript

Node.js

API design

Data modeling

Backend architecture

System reliability

End-to-end ownership

Product instincts

AI tools

High velocity delivery

Tools

Claude Code

Codex

Job description

Affiniti is building the financial operating system for small businesses across America, with the frontend as the bridge. We’re hiring engineers in NYC in-office hybrid with relocation support.

You will own the backend architecture, APIs, data models, and the reliability foundations that scale our product. You’ll also collaborate across product and design to turn ambiguous needs into clean, maintainable systems, sometimes touching frontend as needed.