Principal Engineer Backend

Pennymac•Westlake Village, CA

9h•Onsite

About The Position

Pennymac (NYSE: PFSI) is a specialty financial services firm with a comprehensive mortgage platform and integrated business focused on the production and servicing of U.S. mortgage loans and the management of investments related to the U.S. mortgage market. At Pennymac, our people are the foundation of our success and at the heart of our dynamic work culture. Together, we work towards a unified goal of helping millions of Americans achieve aspirations of homeownership through the complete mortgage journey. Job Overview The Opportunity As a Principal Backend Engineer on the Nexus team, you will be a core architect and builder of the platform's "brain." You won't just be building standard web APIs; you'll be engineering the complex, high-performance backend systems that power our autonomous AI agents, manage our "Unified Context Library," and orchestrate multi-step developer workflows. This role requires a unique blend of elite backend engineering, a deep understanding of developer tooling, and hands-on experience with the new stack of AI-native infrastructure. You will be working directly with your "stakeholders"—other engineers—to understand their pain points and rapidly incorporate their feedback into the tools you build. Why Join Pennymac? Chart Pennymac’s AI Course: This is a greenfield opportunity to join a foundational "internal startup" and build a transformative platform from the ground up, with the stability and resources of an industry leader. High-Impact & Visibility: This AI platform is a top-priority strategic initiative. Your work will be highly visible to senior leadership and will have a direct, measurable impact on the productivity of our entire technology organization. Solve Unique Problems: You'll be tackling cutting-edge challenges in applied AI, developer productivity, and large-scale data orchestration—problems that few companies are solving at this scale. Competitive Compensation: We offer a competitive salary, bonus, and benefits package, including comprehensive health/dental/vision plans, 401(k) matching, and more. Career Growth: We are committed to the growth of our team members and provide opportunities for continuous learning, professional development, and career advancement within a leading FinTech company.

Requirements

Architect and build the core backend systems for the AI SDLC platform in a cloud-native (AWS) environment using Node.js and TypeScript.
Design, implement, and scale the "Unified Context Library," our RAG (Retrieval-Augmented Generation) foundation. This includes ingesting and vectorizing vast amounts of institutional knowledge from sources like Confluence, Jira, and Gitlab.
Develop robust orchestration flows for autonomous AI agents using frameworks like the AWS Bedrock AgentCore and LangChain.ts.
Build and maintain secure, scalable APIs for deep, bi-directional integrations with third-party developer tools (e.g., GitLab, Jira, ServiceNow).
Engineer high-performance developer-focused services (e.g., Language Server Protocol-style backends) that can interact with code repositories, run linters, parse test results, and provide real-time feedback to AI agents.
Collaborate in a highly agile, "internal startup" environment, working directly with product managers and fellow engineers to define, build, and rapidly iterate on new features based on user feedback.
Take full ownership of the services you build, from architectural design and implementation to DevOps (IaC), testing, and production operations.
Recommend and evaluate new technologies, architectures, and processes to ensure our AI platform is scalable, resilient, and cutting-edge.

Responsibilities

Architect and build the core backend systems for the AI SDLC platform in a cloud-native (AWS) environment using Node.js and TypeScript.
Design, implement, and scale the "Unified Context Library," our RAG (Retrieval-Augmented Generation) foundation. This includes ingesting and vectorizing vast amounts of institutional knowledge from sources like Confluence, Jira, and Gitlab.
Develop robust orchestration flows for autonomous AI agents using frameworks like the AWS Bedrock AgentCore and LangChain.ts.
Build and maintain secure, scalable APIs for deep, bi-directional integrations with third-party developer tools (e.g., GitLab, Jira, ServiceNow).
Engineer high-performance developer-focused services (e.g., Language Server Protocol-style backends) that can interact with code repositories, run linters, parse test results, and provide real-time feedback to AI agents.
Collaborate in a highly agile, "internal startup" environment, working directly with product managers and fellow engineers to define, build, and rapidly iterate on new features based on user feedback.
Take full ownership of the services you build, from architectural design and implementation to DevOps (IaC), testing, and production operations.
Recommend and evaluate new technologies, architectures, and processes to ensure our AI platform is scalable, resilient, and cutting-edge.

Benefits

Comprehensive Medical, Dental, and Vision
Paid Time Off Programs including vacation, holidays, illness, and parental leave
Wellness Programs, Employee Recognition Programs, and onsite gyms and cafe style dining (select locations)
Retirement benefits, life insurance, 401k match, and tuition reimbursement
Philanthropy Programs including matching gifts, volunteer grants, charitable grants and corporate sponsorships

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