Senior Frontend Engineer, Shopping Interfaces

You own and build the interactive frontend architecture and production surfaces where a person asks an AI what's actually true about a purchase: our /shop Verification Checker, our streaming conversational shopping assistant, the SimplyCodes browser extension at checkout, and the pages a shopper lands on from search.

Product.ai is the verification layer for commerce: when a person or an AI agent needs to know what's actually true about a purchase, we answer with proof. SimplyCodes is the first proof at scale, the code verification service, at ~$22M a year in revenue. Profitable. Founder-owned since 2009, bootstrapped, no outside investors, no board. Fewer than twenty operators.

Why This Role Exists

We are shipping several high-leverage consumer surfaces at once: our /shop Verification Checker (where any shopper pastes what an AI, an article, a brand page, or a friend told them to buy, and we grade the claims inside it across five verification states - free to consumers to win trust and habit while AI shopping agents pay per call for verified commerce truth), our conversational shopping assistant that streams verified answers with proof beside them, and the SimplyCodes browser extension and web pages that millions of shoppers use every day.

We need a senior frontend architect and builder who owns the interactive frontend end to end: streaming state machines, motion physics, the /shop Design Record component architecture, responsiveness, perceived performance, and accessibility across every consumer surface. You partner directly with our Founding Designer and the founder to set and raise the consumer design and engineering bar.

This is not "implement the mockup." Our design system is executable law, and its tokens and components in the /shop Design Record are read directly by the coding agents that accelerate our builds. You own the hard interactive components, the state and streaming architecture, and the live production interfaces end to end.

The System You'll Need to Model

• The Verification Checker and a conversational surface that streams proof. Whether a shopper pastes a recommendation into our Verification Checker or asks a question in chat, the interface grades claims across five verification states, streams tokens and citations in real time, and lets the user inspect evidence beside the verdict. Streaming state, optimistic updates, interruption, and motion physics are first-class engineering problems.
• A browser extension at the moment of checkout. The SimplyCodes extension runs inside thousands of merchant checkout pages, where DOM structures shift and a shopper has seconds of patience. You co-own the interactive experience, state transitions, and timing that make checkout verification feel instantaneous.
• Pages built for both shoppers and search engines. Our SimplyCodes and Truth Graph pages serve both human shoppers deciding what to trust and search engines indexing verified answers, where Core Web Vitals and perceived speed directly drive trust and distribution.
• The /shop Design Record and a design system agents build inside. Master tokens, components, and rules precise enough that coding agents generating a screen stay within the bar. You co-own and extend that component architecture in React and TypeScript.
• Perceived performance and accessibility as product features. Sub-frame responsiveness, layout stability, keyboard navigation, and screen-reader paths: a trust interface that stutters or drops state loses the user before the verdict loads.
• Cortex, the shared AI brain the company runs on. You work inside it daily, directing coding agents as force multipliers the way our founder does, and since August any operator here can change the rules the company runs on, live, without waiting on founder approval.

If reading that energizes you, keep going. If it feels overwhelming or underspecified, this isn't the right fit.

What You Will Own

• Live production interfaces and frontend architecture, end to end. The interactive frontend of the /shop Verification Checker, the conversational shopping assistant, and its evidence side panel: streaming answers, five-state claim grading UI, state machines, motion physics, interruption, and recovery in React and TypeScript. You partner directly with our Founding Designer and the founder to set and raise the consumer bar.
• The /shop Design Record components and hard interactive primitives. Streaming lists, citation drawers, fluid resizers, and state-carrying transitions - built cleanly once in the design system so both engineers and coding agents compose with them everywhere.
• The SimplyCodes browser extension and web experience. What a shopper sees and interacts with at checkout and on merchant pages: the state transitions, motion, timing, and visible polish.
• Perceived interaction performance and accessibility across all consumer surfaces. Responsiveness, loading states, layout stability, focus management, and screen-reader paths, measured and held to an uncompromising bar.
• Your seat charter. Within your first quarter you co-sign a charter for this seat: one machine-checkable number that proves the seat is working, and a high-ownership partnership model with the founder.

The craft you must already own: senior production frontend engineering in React and TypeScript; a live portfolio or GitHub of shipped interactive work where states and motion physics are visible; modern CSS and animation primitives; web performance and accessibility; and AI coding tools as force multipliers you verify by hand. Bonus: browser-extension or mobile-web architecture and strong visual taste.

Who You Are

How you think. You see an interface as a deterministic state machine with a person inside it: every state the screen can enter, what it communicates in each one, and how transitions preserve context. You reason about correctness, edge cases, and failure modes before writing code, because a streaming interface that works "most of the time" is broken.

How you work. A coding agent, a browser, and a profiler open together, most of the day. You use AI tools as force multipliers and verify every line and interaction because you have deep mastery of the platform. You ship the interaction, measure it in production, and refine what the measurement reveals.

What you've probably built. Interfaces real people used that you can show live: a streaming chat or real-time surface that stayed rock-solid under interruption, a browser extension that thrived in the wild, or a component library other engineers relied on daily. Years matter less than the artifact.

Who this isn't for. Wrong if you want a ticket queue of static mockups to translate into code; here you co-own the frontend architecture, component system, and interaction quality end to end. Wrong if you'd ship an interaction just because the happy path works on your laptop; here it works across every verification state, screen size, and keyboard path, or it isn't done.

How We Hire

We don't run traditional engineering interviews. Every stage is demonstrated performance on work-relevant tasks.

Async video screen (or Fast-Track Portfolio/GitHub review). About 15 minutes, on your own time - or share a standout GitHub profile or live portfolio of shipped interactive frontend work on your application to fast-track straight to stakeholder and founder conversations.

Calls with company stakeholders. Short conversations with the people you'd build beside, including our Founding Designer and engineering peers.

Conversation with the founder. How you reason about frontend architecture, the Verification Checker, and the surfaces above, and what you'd elevate first.

Paid work trial (PRJ-76). A paid real-work trial taking a live interactive component or streaming verification flow from spec to shipped production React/TypeScript inside our /shop Design Record.

If the work above sounds like yours but your resume is unconventional, apply anyway. We hire on the work and the reasoning, not the pedigree.

Compensation & Ownership

Total first-year comp: $400,000 to $500,000 (base + performance-based PIU ownership and profit-share program). Base: $250,000 to $320,000, top of market for senior front-end engineering.

Product.ai is a profitable, founder-owned company generating ~$22M/yr in revenue with zero venture debt. Beyond base salary, senior operators participate in our Profit Interest Unit (PIU) ownership and profit-share program ($0 strike price units sharing directly in annual free-cash-flow distributions and annual company tender liquidity, earned on performance milestones after joining, never day-one vesting); 100% family premium coverage; and an uncapped token budget steered by return.

Based in Santa Monica, Los Angeles, on our high-trust hybrid rhythm: four focused in-office half-days (Mon/Tue/Thu/Fri 9am-2pm), with Wednesdays and afternoons open to work from wherever you do your best work. Relocation support available.