Principal Frontend Engineer, AI

Private National Mortgage Acceptance Company, LLC; Carrollton (TX); On-site; USD 140,000 - 180,000; Full time

Job summary

Pennymac is building an AI-powered frontend platform to empower engineers and product teams. You will architect a scalable frontend workspace using React, TypeScript, and Next.js, enabling real-time collaboration and AI-driven UI components.

You will lead DX efforts, integrate AI APIs, and shape the user experience with innovative visualizations and multi-user workflows, while partnering with backend engineers to define robust APIs.

Qualifications

• Bachelor's degree required in CS or related field.
• 8+ years of elite frontend engineering in SPAs is preferred.
• Expertise in React, TypeScript, Next.js, and modern frontend architectures.
• Experience with real-time collaboration tools and CRDTs is a plus.
• Experience integrating AI APIs and building Generative UI is desired.
• Strong data visualization experience with libraries like D3 or Recharts.
• Demonstrates ownership, initiative, and startup mindset.

Responsibilities

• Architect the Agentic Workspace: design core frontend architecture using React, TS, Next.js for sub-second performance with real-time streams.
• Build the Collaborative Canvas: implement real-time, multi-user workspace with CRDTs and WebSocket infrastructure.
• Master the Generative UI: develop component registry and rendering engine for dynamic AI-driven UI elements.
• Visualize Intelligence: create visualizations to show AI reasoning and sources from tools like Jira/Confluence/GitLab.
• Partner with Backend: define API contracts (GraphQL, streaming JSON) for efficient frontend consumption.
• DX Leadership: improve frontend DevOps, testing strategies, and establish AI-native design patterns.
• Establish Frontend Standards: evangelize patterns and ensure scalable frontend architecture.

Skills

React & TypeScript

Next.js

Real-time collaboration

Generative UI

DX leadership

Performance optimization

Education

Bachelor's Degree in Computer Science or related field

Tools

WebSockets / SSE

Yjs / Automerge

Liveblocks

GraphQL

D3 / Recharts

OpenAI API

Job description

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 homeownership through the complete mortgage journey.

Job Overview

The Principal Engineer is responsible for owning technical design and understanding the tradeoffs in software products. As the Engineer, you will diagnose, document, and troubleshoot systems to resolve problems identified through testing, as well as implement strategies to improve integration and efficiency.

The Principal Engineer will:

• Debug and solve product wide complex issues by translating business problems into technical solutions


• Master knowledge in major parts of the product line technology stack and maintains technical ownership of significant components of its code base


• Identify and solve systemic architectural problems at the subproduct or team level


• Collaborate across teams and build systems to address architectural gaps, and establish, contribute to, and drive best practices across teams


• Demonstrate sustained track record of creating improvements in subproducts or systems around stability, performance, and scalability


• Perform other related duties as required and assigned


• Demonstrate behaviors which are aligned with the organization’s desired culture and values

A Typical Day

The Pennymac Technology Team is building a new division to fundamentally change how we build software. We are creating an AI-powered platform designed to be a force multiplier for our entire Digital Technology Organization. Our mission is to build the next generation of intelligent developer tools that will accelerate our SDLC, automate tasks, and empower our product and engineering teams to deliver industry-leading mortgage technology faster than ever before.

This is a small, tight-knit, and fast-moving team working to rapidly build and deploy new AI tools that directly serve our fellow engineers and product managers. We are looking for a passionate, hands‑on technologist to be a foundational member of this team.

The Opportunity

As a Principal Frontend Engineer on the AI Platform Services team, you will be the architect of the platform's \"face\" and the guardian of the user experience. While the backend team builds the \"brain\" (RAG pipelines and autonomous agents), you will build the \"Collaborative Canvas\"—the interface where human ingenuity meets artificial intelligence.

You will not just be building standard dashboards; you will be engineering complex, AI-native interfaces that rival commercial tools like Cursor and Linear. You will solve unique challenges in Generative UI, real‑time state synchronization, and browser‑based code editing. You will define how our engineers interact with autonomous agents, moving beyond simple \"chatbots\" to build a deeply integrated, multi‑modal workspace that feels like a natural extension of the person's mind.

This role requires a unique blend of elite frontend engineering, a deep understanding of developer tooling (IDEs, CI/CD interfaces), and a visionary approach to Human‑Computer Interaction (HCI) in the age of AI.

Why Join Pennymac?

• Chart Pennymac’s AI Course: This is a greenfield opportunity to join a foundational team and build a transformative platform from the ground up, with the stability and resources of an industry leader.


• Define the AI Interface: This is an opportunity to invent new UI patterns for \"Agentic Workflows.\" You will move beyond static forms to build interfaces that generate themselves based on user intent and AI context.


• High‑Impact & Visibility: Nexus is a top‑priority strategic initiative. Your work will be the primary touchpoint for senior leadership and hundreds of engineers, directly impacting the \"Idea‑to‑Production\" velocity of the entire organization.


• Solve Unique Problems: You will tackle cutting‑edge challenges in Collaborative Editing (CRDTs), Streaming UI, and Visualizing Complex Agent Reasoning—problems that sit at the bleeding edge of modern web development.


• 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.

What You\'ll Do (Responsibilities)

• Architect the Agentic Workspace: Design and build the core frontend architecture for the AI platform using React, TypeScript, and Next.js, ensuring sub‑second performance even with heavy data visualization and real‑time streams.


• Build the \"Collaborative Canvas\": Engineer a real‑time, multi‑player workspace where AI agents and humans can co‑author artifacts (User Stories, PRDs, Architecture Diagrams). Implement CRDTs (Conflict‑Free Replicated Data Types) and WebSocket infrastructures to manage shared state seamlessly without data loss.


• Master the \"Generative UI\": Develop a robust component registry and rendering engine that allows AI agents to dynamically generate interactive UI elements (charts, forms, checklists) on the fly, rather than just outputting text.


• Visualize Intelligence: Create intuitive visualizations for the \"Unified Context Library\", allowing users to see why an AI agent made a decision, trace its sources (Jira, Confluence, GitLab), and inspect its reasoning graph via interactive diagrams.


• Partner with the Backend: Collaborate closely with Principal Backend Engineers to define the API contracts (GraphQL, Streaming JSON, Server‑Sent Events) that enable the frontend to consume complex agent outputs efficiently.


• Developer Experience (DX) Leadership: Work directly with your \"customers\" (Pennymac engineers and product analysts) to understand their workflows. Translate their friction points into elegant UI solutions that reduce context switching.


• Establish Frontend Standards: Take ownership of the frontend DevOps pipeline, testing strategy (E2E/Integration), and architectural standards. Evangelize \"AI‑Native\" design patterns across the broader technology organization.

What You\'ll Bring

Must‑Haves:

• Bachelor\’s Degree in Computer Science, HCI, or related engineering disciplines, or equivalent professional experience.


• Elite Expertise in React & TypeScript: A proven track record (8+ years) of building complex, data‑heavy Single Page Applications (SPAs). Deep mastery of React internals, hooks, context, and performance optimization.


• Next.js & Server Components: Experience with modern Next.js architectures (App Router), specifically leveraging Server Components and streaming for progressive UI rendering.


• Real‑Time Collaboration Experience: Hands‑on experience building multi‑user, real‑time applications using WebSockets, SSE, or libraries like Yjs, Automerge, or Liveblocks. You understand the complexities of state synchronization and conflict resolution in distributed systems.


• \"Generative UI\" / AI Integration: Demonstrable experience integrating LLM APIs (OpenAI, Anthropic, AWS Bedrock) into frontend applications. Experience with \"streaming\" UI responses and handling unstructured data.


• Data Visualization: Proficiency with visualization libraries (e.g., D3.js, Recharts, React Flow, or Mermaid.js) to render complex dependency graphs and architecture diagrams.


• A \"Startup Mentality\": High ownership, collaborative spirit, and adaptability. You are comfortable shipping an MVP \"Collaborative Canvas\" one week and refactoring it for scale the next based on user feedback.

Nice‑to‑Have (Bonus Points):

• Experience with AI SDKs: Familiarity with the Vercel AI SDK, LangChain.js, or similar frameworks for managing agentic state in the frontend.


• Design Systems: Experience building or maintaining enterprise‑grade Design Systems (e.g., using Tailwind CSS, Radix UI, or Shadcn).


• Backend Fluency: Ability to write Node