Senior Software Engineer / PoS & Payments / NYC

$220000 - $300000

Job Description

A growing software company is building an integrated platform that helps independent retailers manage store operations, payments, online sales, inventory, and financial workflows. The company combines retail technology with AI-powered tools to help local businesses operate more efficiently and compete with larger organizations.

As a Senior Software Engineer you’ll build and own financial systems spanning payroll, bill pay, embedded banking, accounting integrations, and ledgers. You’ll be one of the first engineers developing the payroll product, helping move the platform beyond recording financial activity to executing payments and managing money.

This is a hands-on engineering role where correctness, reliability, and auditability are essential. You’ll design double-entry ledgers, implement idempotent payment execution, build reconciliation processes, and investigate financial discrepancies down to their root cause. You’ll partner closely with platform engineers and retail customers while establishing financial engineering standards that other teams can adopt.

The engineering team ships frequently and uses AI coding agents as part of its daily workflow. You’ll direct, review, and productionize agent-written code while maintaining the safeguards required for systems that handle money.

Required Skills & Experience

• 5+ years of experience building production backend systems

• Strong ability to write correct, maintainable, and reviewable code

• Practical understanding of transactional guarantees, including idempotency, atomicity, retry behavior, and duplicate webhook handling

• Deep PostgreSQL experience, including clear schema design, transactions under concurrency, and query performance as data volumes grow

• Strong attention to financial accuracy, including reconciliation, rounding, and precise tax calculations

• Experience investigating production issues, identifying root causes, and implementing solutions that prevent recurring classes of bugs

• Comfort taking ownership in a small team where engineering decisions help establish broader technical standards

Desired Skills & Experience

• Experience with TypeScript and Node.js

• Experience building payroll, banking, ledger, or other financial systems with auditable data models

• Experience with accounting integrations such as QuickBooks, NetSuite, or Xero

• Familiarity with payment processors or ACH payment rails

• Experience with Next.js, tRPC, Prisma, Vercel, ElastiCache, or RDS/RDS Proxy

• Experience directing AI coding agents such as Devin, Claude Code, or Cursor and implementing safeguards for their use

• Retail or point-of-sale experience, particularly with multi-location operations or cash reconciliation

• Experience establishing technical standards or architectural principles adopted across teams

What You Will Be Doing Daily Responsibilities

• Build a payroll product from the ground up, including earnings calculations from shift data, tax withholding, payment execution, and integrations for tax filings

• Develop bill pay capabilities that allow retailers to manage supplier payments and accounts payable directly within the platform

• Integrate bank accounts into the platform to help customers access card-processing revenues within minutes

• Own and strengthen accounting integrations, including QuickBooks synchronization for invoices, bills, cost-of-goods-sold journal entries, and sales mappings

• Design and maintain accurate, idempotent, and auditable ledgers for loyalty programs, gift cards, and deposits

• Ensure ledger systems remain correct under concurrent writes

• Establish reusable financial engineering patterns, including double-entry accounting, idempotency keys, reconciliation jobs, and timezone-aware cutoffs

• Investigate production discrepancies and trace financial activity from customer reports to underlying transactions and system behavior

• Partner with platform engineering on the sales data and transaction flows consumed by financial systems

• Work directly with retail customers to understand payroll and financial operations

• Use AI coding agents to accelerate development while carefully reviewing and validating money-handling code

The Offer

• Base salary of $220,000–$300,000, based on experience, skills, and scope of responsibilities

• Meaningful early-stage equity

• Fully company-covered medical and dental benefits

• 401(k)

• Weekly catered lunches and evening dinners for employees who wish to participate

• Opportunity to help build foundational payroll and money movement products

• High ownership over financial architecture and engineering standards

• Direct collaboration with platform engineers and the customers using the software

Applicants must be authorized to work in the US on a full-time basis now and in the future.

Motion Recruitment Partners (MRP) is an Equal Opportunity Employer. All applicants must be currently authorized to work on a full-time basis in the country for which they are applying, and no sponsorship is currently available. Employment is subject to the successful completion of a pre-employment screening. Accommodation will be provided in all parts of the hiring process as required under MRP’s Employment Accommodation policy. Applicants need to make their needs known in advance.