Senior Software Engineer - Node / React

Simplex Hires LLC; New York (NY); On-site; USD 180,000 - 220,000; Full time

Benefits offered by this job

Unlimited PTO

Full benefits package including medical, dental, and vision

401(k) plan

Transportation benefits

Job summary

Simplex Hires LLC is looking for a Senior Engineer to join their fast-growing tech company in New York, NY. The role involves building new user-facing features, enhancing observability in existing systems, and collaborating cross-functionally to develop innovative solutions.

Candidates should have at least 5 years of engineering experience and a strong foundation in programming. The position offers a salary range of $180K–$220K along with unlimited PTO and a full benefits package.

Qualifications

• At least 5 years of experience in software engineering.
• Strong foundation in computer science and programming.
• Hands-on experience with designing APIs and abstractions.

Responsibilities

• Build and own new user-facing features from end-to-end.
• Continuously improve observability across existing systems.
• Collaborate with product and engineering to architect differentiators.
• Build CI/CD pipelines to increase development velocity.

Skills

Serverless architectures

Node.js

React

Next.js

Typescript

AWS

PostgreSQL

Terraform

Job description

Our client is a fast-growing, venture-backed technology company that has built a modernized Point-of-Sale (POS) platform purpose-built for a niche industry. Two years in, they have achieved meaningful scale — serving 150+ multi-location enterprise customers with a system that operates around the clock across multiple time zones, acting as the core platform for procurement, transactions, and reporting.

They work fully in-person, 5 days a week, out of their office in the Flatiron district of New York City. Relocation assistance and visa sponsorship are not available at this time.

Who They're Looking For

As a Senior Engineer, you'll be expected to bring strong engineering principles backed by at least 5 years of experience. The ideal candidate:

• Has a strong computer science and programming foundation — has read Designing Data-Intensive Applications
• Is a craftsperson who deeply cares about the quality of their output and understands the long-term costs of shortcuts
• Builds with the end user and longevity in mind — knows how to design abstractions and APIs that are a pleasure for both customers and teammates to use
• Communicates effectively to drive clarity and alignment across the organization — able to translate product requirements into technical challenges and vice versa
• Is genuinely passionate about software engineering and dives deep into topics that interest them, whether that's the Node.js Event Loop or how virtual memory works at the OS level
• Has hands-on experience with serverless architectures — comfortable designing and deploying serverless functions and event-driven systems in cloud environments (e.g., AWS Lambda, Vercel Edge Functions, or equivalent)

What You'll Work On

• Build and own new user-facing features end-to-end, from database models to UI components
• Continuously improve observability across existing systems — analytics, monitoring, and alerting
• Collaborate with product and engineering to architect key differentiators, including embedded fintech products and AI agents to help merchants manage their stores
• Build CI/CD pipelines and developer tooling (e.g., feature environments) that increase development velocity
• Help shape engineering processes to support building a world‑class product

Tech Stack

Familiarity with every tool isn't required, but candidates should have the foundational knowledge to understand what powers them under the hood:

• Node
• React
• Next.js deployed on Vercel
• Typescript
• AWS (particularly RDS)
• PostgreSQL
• Terraform or equivalent infrastructure-as-code tooling

Compensation & Benefits

• Salary: $180K–$220K + meaningful equity, depending on experience
• Unlimited PTO
• Full benefits package: medical, dental, vision, 401(k), transportation, and more