Senior Software Engineer; Node.js​/React

About Applied Business Software, Inc.,

Applied Business Software, Inc., (ABS), the maker of The Mortgage Office®, is the industry leader in private lending and loan management technology. Since 1978, our software has powered thousands of lenders, including private money firms, municipalities, CDFIs, Tribal Nations, universities, franchisors, third‑party servicers and other non‑bank lenders, helping them streamline, automate, and scale their lending operations with confidence.

The Mortgage Office is looking for a Senior Software Engineer (Back‑End) to architect and scale the core systems powering our platform. This is a backend‑leaning full stack role (~70% backend, 30% frontend). We need a true backend builder who can design and implement scalable, secure microservices, while also being comfortable contributing to our React‑based frontend when needed. This is not a support role.

This is a high‑ownership engineering role focused on system design, API development, data architecture, and secure multi‑tenant SaaS systems.

• Architect and implement scalable backend services using Node.js (
  Nest.js framework) in a microservices environment
• Design and build APIs from scratch — including schema design, validation, authentication, and lifecycle management
• Own database design, optimization, and data modeling
• Build and maintain data pipelines, messaging systems, and analytics storage
• Contribute to frontend development in React to support end‑to‑end feature delivery
• Collaborate cross‑functionally to deliver complete features from backend services to UI
• Drive architectural decisions that improve scalability, performance, and security

• Hands‑on experience building services using Nest.js
• Strong understanding of distributed systems and service communication patterns

• Built APIs (not just consumed them) within the last 2–3 years
• Experience designing RESTful or event‑driven APIs
• Familiar with versioning, validation, documentation, and testing strategies

• Strong database design experience (schema design, indexing, performance tuning)
• Experience building data pipelines and working with messaging systems
• Experience with analytics storage and reporting systems

• Deep understanding of authentication flows and token management (JWT, OAuth, etc.)
• Experience designing or operating within multi‑tenant architecture
• Strong awareness of common security vulnerabilities and prevention methods
• Experience implementing role‑based access controls and secure API patterns

• Strong working experience with React
• Ability to build and maintain production‑ready UI components
• Comfortable connecting frontend to backend APIs you’ve built
• Understanding of state management and frontend performance optimization

• 5+ years of full stack experience, with strong backend depth
• Experience owning systems or features from design through deployment
• Strong systems‑thinking mindset
• Ability to operate independently in a high‑impact role
• Experience in SaaS or multi‑tenant environments is highly preferred

• Comprehensive health, dental, and vision coverage.
• 401(k) with company funded match.
• Mission‑driven company with a 45+ year legacy and industry‑leading products trusted by thousands of lenders.
• Collaborative, supportive team known for long tenure, deep expertise, and a culture built on trust and integrity.
• Help modernize and evolve the leading platform in private lending technology.
• Beautiful San Mateo office with a tight‑knit culture.
• Competitive compensation and room for professional growth.
• Performance‑based bonuses.
• Generous PTO.
• Modern workspace with on‑site amenities.
• Awesome company Christmas party.

The pay range for this role is: 160, USD per year (San Mateo, CA)