Senior Software Engineer, Backend – Platform & API Development - 411163

Atrium; New York (NY); On-site; USD 190,000 - 210,000; Full time

Benefits offered by this job

Equity compensation.

Job summary

Atrium, a rapidly growing technology company, is seeking a Senior Software Engineer, Backend – Platform & API Development to design, build, and scale its core platform and external API infrastructure. You will own backend systems, API design, and transactional workflows across bookings, payments, and inventory.

The role is hands-on with significant technical ownership, offering opportunities to advance into Staff Engineer and to contribute to architectural decisions within a collaborative,

Qualifications

• 6+ years of professional software engineering experience in backend or platform development.
• Proven ability to design, develop, and deploy complex backend systems.
• Experience building external APIs and third-party integrations.
• Experience with transactional workflows involving payments, orders, bookings, or inventory.
• Strong relational database and data modeling skills.
• Solid CS fundamentals and problem-solving abilities.
• Experience in established engineering organizations with strong standards.
• Ability to own projects and drive architectural decisions.
• Excellent communication and collaboration abilities.
• Ability to work onsite in New York City four days per week.

Responsibilities

• Design, develop, and maintain scalable backend systems for a high-growth platform.
• Build and maintain external-facing APIs and third-party integrations.
• Develop transactional workflows for reservations, bookings, inventory, and payments.
• Own backend architecture, API design, and implementation decisions.
• Design relational database models emphasizing consistency and scalability.
• Collaborate with senior engineers on architecture and long-term strategy.
• Develop reusable patterns to support future platform integrations.
• Partner with product managers to translate requirements into technical solutions.
• Write, test, deploy, and maintain production-grade code.
• Identify opportunities to improve system performance and reliability.

Skills

Backend development

API design

Distributed systems

Payments and bookings flows

Data modeling

Communication

Education

Bachelor's degree

Tools

PostgreSQL

Ruby on Rails

Node.js

AWS

Redis

OpenSearch

Job description

Client Overview

Our client is a rapidly growing, profitable technology company operating a digital marketplace that connects consumers and businesses through innovative technology solutions. The organization is continuing to expand its platform, product offerings, and engineering team to support increasing demand and is seeking a

Client Overview

Our client is a rapidly growing, profitable technology company operating a digital marketplace that connects consumers and businesses through innovative technology solutions. The organization is continuing to expand its platform, product offerings, and engineering team to support increasing demand and is seeking a Senior Software Engineer, Backend – Platform & API Development.

With a strong focus on technical excellence, collaboration, and innovation, the company offers engineers the opportunity to take ownership of meaningful projects, contribute to architectural decisions, and build scalable systems that support long‑term growth.

Salary/Hourly Rate

$190k - $210k

Position Overview

A Senior Software Engineer, Backend – Platform & API Development will help to design, develop, and scale its core platform and external API infrastructure. This individual will play a critical role in building reliable backend systems, developing third‑party integrations, and supporting complex transactional workflows involving bookings, payments, inventory, and reservations. The ideal candidate has strong computer science fundamentals, experience developing scalable production systems, and the ability to independently own technical projects from initial design through deployment. This is a hands‑on individual contributor opportunity offering significant technical ownership, collaboration with experienced engineering leadership, and potential advancement into a Staff Engineer position.

Responsibilities of the Senior Software Engineer, Backend – Platform & API Development

• Design, develop, and maintain scalable backend systems supporting a high-growth digital platform.
• Build and maintain external-facing APIs and integrations with third-party platforms.
• Develop reliable transactional workflows involving reservations, bookings, inventory, and payments.
• Take ownership of backend architecture, API design, and technical implementation decisions.
• Design relational database models with an emphasis on consistency, scalability, and data integrity.
• Collaborate with senior engineers on foundational architecture and long‑term technical strategy.
• Develop reusable engineering patterns to support future platform integrations.
• Partner with product managers and cross‑functional stakeholders to translate business requirements into technical solutions.
• Write, test, deploy, and maintain high-quality production code.
• Identify opportunities to improve system performance, reliability, and engineering efficiency.

Required Experience/Skills for the Senior Software Engineer, Backend – Platform & API Development

• 6+ years of professional software engineering experience, primarily focused on backend or platform development.
• Proven experience independently designing, developing, and deploying complex backend systems.
• Strong experience building external-facing APIs and integrating with third-party services.
• Experience developing transactional systems involving payments, orders, bookings, reservations, inventory, or similar workflows.
• Strong understanding of relational databases, data modeling, data consistency, and backend architecture.
• Solid computer science fundamentals and strong technical problem‑solving abilities.
• Experience working within an established engineering organization with strong technical standards and best practices.
• Demonstrated ability to take ownership of technical projects and make sound architectural decisions.
• Strong communication and collaboration skills.
• Ability to quickly learn new technologies and adapt to evolving technical requirements.
• Interest in remaining hands‑on with software development.
• Ability to work onsite in New York City four days per week.

Preferred Experience/Skills for the Senior Software Engineer, Backend – Platform & API Development

• Experience with Ruby on Rails, Node.js, PostgreSQL, and AWS.
• Familiarity with Redis, Kafka, Datadog, or OpenSearch.
• Experience developing high‑volume transactional platforms, marketplaces, payment systems, or booking applications.
• Experience building scalable API infrastructure and complex third‑party integrations.
• Background at a well‑established technology company or high‑performing product engineering organization.
• Experience working in a rapidly growing startup environment.
• Familiarity with AI‑assisted development tools, including LLM coding agents.
• Experience owning technical initiatives from initial architecture through production deployment.

Education Requirements

• Bachelor's degree in Computer Science, Software Engineering, or a related technical field preferred. Equivalent professional experience and demonstrated technical expertise will also be considered.

Benefits

• Equity compensation.
• Opportunity for career advancement into Staff‑level engineering positions.
• Significant ownership of technical projects and architectural decisions.
• Collaborative engineering environment with experienced technical leadership.
• Opportunity to work on innovative, scalable technology solutions.