Senior Frontend Engineer, Shopping Interfaces

Description

You will build and own the interactive frontend for the moments when a shopper asks whether a purchase holds up: the shopping verification checker, a streaming conversational assistant, the browser extension that appears at checkout, and the pages people land on from search.

The company verifies commerce claims for people and AI agents, answering with evidence. Its code verification service is the first large-scale proof, bringing in about $22M a year. The company is profitable and debt-free, has been founder-owned since 2009, is bootstrapped, takes no outside investors, has no board, and has fewer than twenty operators.

The team is shipping several consumer surfaces at once. The checker lets any shopper paste in advice from an AI, an article, a brand page or a friend, then grades the claims across five verification states. It is free for consumers to build trust and habit, while AI shopping agents pay per call for verified commerce facts. The assistant streams verified answers with proof beside them. The extension and web pages are used daily by millions of shoppers.

This is a hands-on senior role. You co-own the frontend architecture, component system and interaction quality, working directly with the Founding Designer and the founder. The design tokens and components are read by the coding agents that speed up builds, so you own the hard interactive pieces and the state and streaming design behind them.

Core problems include streaming state, optimistic updates, interruption, motion, layout stability on checkout pages whose structure shifts, accessibility, and pages that must rank in search while helping people decide what to trust.

Responsibilities

• Build and maintain the live production interfaces in React and TypeScript, including streaming answers, five-state claim grading, the evidence side panel, interruption and recovery.
• Design the state machines and transitions for every screen state, and make sure context survives each change.
• Build reusable interactive primitives in the design system, such as streaming lists, citation drawers, fluid resizers and transitions that carry state, so engineers and agents can compose them.
• Own the extension's interactive experience at checkout: transitions, timing, motion and polish, including when merchant page structures shift.
• Own responsiveness, loading states, layout stability, focus management and screen-reader paths across all consumer surfaces, held to a strict bar.
• Work with the Founding Designer and the founder to set and raise the consumer design and engineering bar.
• Direct AI coding tools and verify their output line by line and in the browser.
• Within your first quarter, co-sign a charter for the seat with one machine-checkable number that shows the seat is working.

Requirements

• Treat each interface as a deterministic state machine with a person inside it. Reason through states, edge cases and failure modes before writing code.
• Work with a coding agent, a browser and a profiler open at once. Verify every line and interaction yourself, ship, measure in production, and refine based on what you find.
• Senior production frontend experience in React and TypeScript, with a live portfolio or GitHub showing interactive work where states and motion are visible.
• Strong command of modern CSS and animation primitives, web performance, and accessibility.
• Evidence of real interfaces people used: a streaming or real-time surface that held up under interruption, a browser extension used in the wild, or a component library other engineers relied on. Track record matters more than years.
• Bonus: browser extension or mobile-web architecture, and strong visual taste.
• This is not for you if you want to turn a queue of static mockups into code, or if you would ship something that only works on the happy path.

Conditions

First-year total compensation of $400,000 to $500,000, made up of a base salary of $250,000 to $320,000 plus performance-based PIU ownership and profit-share.

Based in Santa Monica, Los Angeles, on a hybrid schedule: four in-office half-days, Monday, Tuesday, Thursday and Friday, 9am to 2pm. Wednesdays and afternoons are open to work from wherever you do your best work.

Relocation support is available.

Benefits

• Profit Interest Units with a $0 strike price, sharing in annual free-cash-flow distributions and annual company tender liquidity. Units are earned on performance milestones after joining, never vesting on day one.
• 100% family premium coverage.
• An uncapped token budget, steered by return.