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.
About the role 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.
What you'll do- 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
- Backend Focus & Requirements (Core of the Role)
Microservices Architecture- Hands-on experience building services using Nest.js
- Strong understanding of distributed systems and service communication patterns
API Ownership- 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
Data & Systems Depth- 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
End-to-End Security Understanding- 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
Frontend Expectations (30%)- 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
Qualifications- 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
Why Join Us?- 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:
160,000 - 180,000 USD per year (San Mateo, CA)
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