Senior Software Engineer, Onboarding

About the role

You will collaborate with cross-functional partners to design and deliver the foundational onboarding experience that defines the first impression new customers have with Justworks. You will own the architecture and implementation of backend services that unify disparate onboarding flows into a single, coherent journey. This role requires deep engagement with sensitive identity and payroll data while applying rigorous testing practices to ensure reliability and security. You will leverage service-oriented patterns and automated testing to build scalable and maintainable solutions. You will work closely with product managers, designers, and other engineers to scope, design, and iterate on new functionality. Your work will directly influence activation rates, time-to-first-payroll, and overall onboarding completion. You will champion observability and best practices to ensure systems are secure, performant, and maintainable.

Key facts

What you'll do

• Collaborate with a cross functional team to design a next-generation platform to unlock new business capabilities.
• Take ownership of designing and implementing APIs, systems integrations and backend services.
• Promote engineering excellence through technical leadership, knowledge-sharing and mentorship.
• Instate best-practices observability and monitoring as "first principles" of all our services.
• Keep extremely sensitive data compartmentalized and secure.
• Perform other related duties as assigned.
• Translate complex business requirements into scalable technical solutions while maintaining a focus on user experience.
• Partner with product and design to iterate on prototypes and define technical feasibility for new onboarding features.
• Write clean, testable code that accelerates delivery and reduces long term maintenance burden.
• Troubleshoot production issues with ownership and urgency alongside product and operations teams.
• Drive alignment across engineering, product, and operations to remove blockers and streamline onboarding workflows.
• Contribute to roadmap planning by providing technical insights and forecasting effort for new capabilities.
• Mentor junior engineers and share knowledge through code reviews, pair programming, and internal documentation.

Requirements

• You have experience designing and developing large-scale, distributed applications using service-oriented architectures.
• You are comfortable separating data and functionality to achieve modular, maintainable systems.
• You demonstrate mastery of automated testing as a productivity multiplier and a safeguard for production stability.
• You are eager to learn and passionate about continuous improvement in both technology and processes.
• You think deeply about how systems work and how they can be made more reliable, scalable, and secure.
• You have strong written and verbal communication skills to collaborate effectively with cross-functional stakeholders.
• You are comfortable working in an entrepreneurial environment where priorities can shift quickly.
• You have experience working with sensitive and regulated data in a secure manner.

Practical notes

The Senior Software Engineer, Onboarding role at Justworks is centered on transforming a traditionally fragmented and support-heavy onboarding experience into a streamlined, self-serve journey for every new customer. In this position, you will play a critical role in building the first product interaction that many businesses have with the company, directly impacting activation and time-to-revenue. You will work closely with product, design, and operations to understand complex business requirements and translate them into robust technical solutions. The role demands comfort with ambiguity and the ability to prioritize effectively in a fast-paced, entrepreneurial environment.

You will be responsible for designing and implementing APIs and backend services that enable seamless data flow across PEO, ASO, and EOR products. This includes integrating with external systems and internal data platforms while ensuring data integrity and security. A key part of the role is to consolidate multiple onboarding flows into a single, coherent experience that adapts to different hire types, including full-time employees, contractors, and international hires. You will apply automated testing strategies to increase confidence in releases and reduce manual regression efforts. Your work will be guided by principles of observability, ensuring that services are monitored proactively to detect and resolve issues before they impact customers.

The successful candidate will bring strong judgment and resourcefulness to tackle evolving challenges while maintaining a focus on long-term maintainability. You will mentor other engineers by promoting knowledge sharing, conducting thoughtful code reviews, and contributing to technical design discussions. The role requires collaboration with stakeholders across the organization to align technical constraints with business goals. You will help define testing strategies, monitoring dashboards, and incident response practices for the onboarding platform. The position offers the opportunity to work with modern web technologies, though prior experience with Ruby on Rails is not required.

This role is based in New York, New York, and is subject to the company's policies regarding hours, travel, and compliance. Justworks is committed to building a diverse team and encourages qualified candidates from all backgrounds to apply. The work environment is dynamic, requiring adaptability and a willingness to learn new tools and processes. You will be expected to take ownership of your work and drive initiatives that improve both the customer and employee experience. The role is integral to the company's data-driven approach to product development and continuous iteration. If you are passionate about system design, security, and delivering exceptional user experiences, this role provides the opportunity to make a significant impact from day one.