Full Stack Developer; AI Native

Pennymac

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 home ownership through the complete mortgage journey.

We are seeking a Full Stack Developer (AI-Native) to join our Digital Customer Experience (DCX) engineering team. In this role, you will lead the development, optimization, and maintenance of our customer-facing web platforms and APIs. You will act as the primary owner of the transactional payment processing engine, pricing/fee rules, and pipeline automation systems, leveraging cutting‑edge AI coding assistants to drive immense engineering velocity, safety, and codebase elegance.

• Monorepo & Full-Stack Codebase Stewardship: Maintain, scale, and optimize core frontend and backend monorepos containing React (React 19+) web platforms,
  Type Script , and Node.js APIs
  . Ensure robust error handling, secure authentication flows, and high-performance execution.

• Domain Ownership (Payments & Rules Engine): Design, refactor, and safeguard complex payment rules, fee calculation logic, and financial validation flows. Ensure all transactional workflows are highly resilient, compliant, and thoroughly covered by automated test suites.

• AI-Augmented Engineering: Embrace and champion AI coding tools (e.g.,
  Git Hub Copilot, Cursor, Claude Code
  ) to accelerate development velocity, run complex codebase refactoring safely, and generate robust test coverage. Contribute to internal developer tools, AI agent integrations, or LLM-powered features.

• Code Health & Complexity Management: Actively monitor and refactor application files to maintain low cyclomatic complexity. Prevent technical debt buildup by decomposing monolithic codebases (such as routing and state controllers) into testable, modular units.

• Mentorship & AI Standards: Mentor junior and mid-level engineers on AI-augmented coding workflows, prompting best practices, and secure AI-generated code validation.

• CI/CD, IaC & Automation: Own and optimize delivery pipelines and developer work spaces. Configure automated formatting, continuous integration tests (such as cross-platform line endings), and work alongside Dev Ops utilizing Infrastructure as Code (Terraform, CDK, or Cloud Formation) where applicable.

• Education & Experience: Bachelor’s degree in Computer Science, engineering, or related field with 5+ years of professional software development experience (or equivalent practical experience).

• Enterprise Full-Stack Architecture:
  Expert-level proficiency in ReactJS and modern front-end development patterns, alongside strong backend engineering skills in Node.js/Type Script (scalable API design, database schema optimization, secure authentication).

• AI-Native Tooling: Proven track record of incorporating AI coding assistants (Git Hub Copilot, Cursor, LLM-based CLI tooling) into your daily development workflow to dramatically increase delivery speed and code accuracy.

• Monorepo & Complexity Management: Practical expertise managing multi-project work spaces (monorepos) to ensure strict separation of concerns, alongside a proven habit of decomposing complex/monolithic modules into lightweight custom hooks or utilities.

• Payment/Rules Logic: Experience developing financial checkout systems, transactional rules engines, automated payment schedules, or complex business logic flows.

• Cloud & IaC (Preferred): Exposure to cloud environments (
  AWS preferred
  ), containerization, or Infrastructure as Code (
  Terraform, Cloud Formation, or CDK
  ).
• AI Innovation (Preferred): Familiarity with LLM integration, RAG pipelines, or vector databases.

As one of the top mortgage lenders in the country, Pennymac has helped over 4 million lifetime homeowners achieve and sustain their…