Top Senior Software Engineer Jobs in NYC, NY

Lead design and implementation of the payment and clearinghouse platforms powering Headway's revenue flows. Build fault-tolerant, observable integrations (Stripe, Plaid, payers), create abstractions for adjacent teams, mentor engineers, and write high-impact code to ensure reliability, throughput, and correct reconciliation of transactions at scale.

Headway seeks a Staff Fullstack Engineer to own end-to-end product work across frontend and backend. You’ll build practice management, patient/provider engagement, AI-enabled clinical systems, onboarding, growth tools, and platform foundations. The role requires technical leadership, cross-functional strategy, mentoring, and shipping scalable, reliable systems in a complex healthcare domain.

Design and build reliable backend services powering clinical data, insurance billing, patient-facing infrastructure, and financial ledger systems. Scale high-integrity systems requiring idempotency, strong consistency, and pragmatic AI integration to automate provider workflows and enable personalized patient experiences.

Lead frontend-leaning full-stack implementation work for carrier and enterprise integrations: architect reusable UI and API layers, author RFCs, guide technical delivery, enforce testing and security best practices, and partner with cross-functional teams to scope and ship production integrations.

Build and own Eve's marketing site and GTM engineering stack: integrate and optimize external tools, design AI agents for sales and marketing, implement webhooks and middleware to sync product/CRM data, and create programmatic campaigns and internal tools in partnership with Marketing, Sales, RevOps, and Product to drive growth and automation.

As a Senior Software Engineer in Trust & Safety, you'll analyze threats, design systems for abuse detection, and collaborate with teams to implement scalable defenses.

The Senior Software Engineer will oversee Java application frameworks, manage the software development lifecycle, and collaborate on system designs for market operations.

Build and maintain Square Financial Services' banking platform: design fault-tolerant services, onboard products, handle sensitive data with security and compliance, operate and observe critical services, remediate incidents, and create durable fixes while partnering across engineering and finance teams.

Collaborate with business and engineering teams to implement scalable user interfaces, backend services, and risk management systems with a focus on real-time metrics.

Build and operate a hyper-scale data lake and analytics platform: develop Java microservices and Spark/Scala/Flink pipelines, own a new graph database, design ultra-high-scale data platforms, optimize performance and latency, enable efficient querying for analytics and ML, and collaborate on feature design and stability across teams.

As a Staff Software Engineer, you will lead technical strategy for the Cash App Banking team, collaborate on solutions, mentor engineers, and focus on robust, scalable systems for consumer banking needs.

Design, build, test, and operate Gusto core customer-facing products across frontend and backend. Own multi-quarter projects, scale Ruby/Rails and JavaScript/React systems, mentor engineers, collaborate with product, data, design, and platform teams, and iterate on features that deliver measurable customer impact.

Staff Software Engineer to own full-stack features and domain-level architecture for a web-based Medicare broker platform. Deliver frontend and backend work, mentor engineers, shape technical standards, reduce technical debt, collaborate with product/design, and expand use of AI-powered developer tools to improve developer productivity and product outcomes.

The Lead Software Engineer will lead technology projects, develop cloud-based solutions, and work with a team to create a messaging platform for Capital One Travel products.

As a Senior Software Engineer, you'll design and implement backend systems, build APIs, and ensure data security while collaborating with cross-functional teams to unify time tracking and compliance across various platforms.

As a Senior Software Engineer, you will design and implement APIs and backend services, collaborate with teams, and leverage automated testing to improve functionality and security in onboarding applications.

In this role, you'll build and maintain core payroll systems, enhance system performance, lead projects, mentor peers, and ensure platform reliability.

Lead technical design and development of secure, scalable backend services. Write and review Java/Spring code, build RESTful Spring Boot microservices, ensure operational stability, drive CI/CD automation, adopt enterprise AI-assisted engineering practices, and lead technical evaluations and communities of practice.

Lead a portfolio and engineering team to design and deliver cloud-based, distributed microservices and full-stack solutions for regulatory needs. Mentor engineers, evaluate and occasionally write code, collaborate with product managers, and leverage cloud platforms, container orchestration, databases, and emerging technologies to build scalable systems.

As a Backend Engineer at Kalshi, you will design algorithms for order matching, optimize data access, and lead integrations with external clients, contributing to a fast-growing financial market.

As a Frontend Engineer, you'll build and enhance the trading experience, develop user-facing features, and engage with customers to shape product decisions.

Design, build, and maintain scalable, reliable full‑stack systems. Contribute to API and architecture design, write testable code, debug complex issues, improve performance, automate deployments, and mentor junior engineers while collaborating with cross‑functional teams.

Lead architecture and implementation of Zocdoc's interoperability platform integrating 170+ EHRs. Drive a rearchitecture for real-time, fail-fast syncs, design abstractions/APIs for other teams, ship production code, mentor engineers, and influence product and technical strategy to improve reliability, scalability, and developer productivity across the integration stack.

As a Staff Software Engineer, you will enhance the core software platform for leasing, develop features, propose architectural improvements, and drive engineering best practices.

The Senior Software Engineer will lead the development of customer care tools, enhance internal systems, and collaborate across teams to solve customer service challenges using AI and full-stack engineering.