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Sift Stack, Inc. - Senior Software Engineer, Frontend (Agentic AI)

Marina Del Rey, California, United States$180k - $230k+ Equity2d ago

Requirements

• 8+ years of professional software engineering experience • Get excited about owning a product area: talking to customers, deciding what to build, and shipping it • Have built complex, high-performance web applications with technologies like React, NextJS, TypeScript, or similar • Have an eye for detail: you notice the micro-interactions, latency, drops in FPS, and polish that separate good interfaces from exceptional ones • Are curious about new AI products: you try new agents, models, and features as they ship, and have opinions about what makes them good • If this role excites you, apply even if you don’t check every box. • Shipped products to users at scale: large data volumes, significant active user counts, or deep technical complexity • Shipped LLM-powered features • Built chat or agentic interfaces: streaming responses, tool-call rendering, long-running tasks • A strong understanding of web performance optimization and browser rendering • Worked with modern CSS (Tailwind) and component libraries (Radix UI) to build design systems • Used technical visualization tools (WebGL, D3.js, Apache ECharts), WebAssembly, and time-series data • Built tools for technical users (dashboards, data-editing environments) • A personal ecosystem of AI dev tooling: custom agents, skills, scripts, or workflows built to ship faster • A background in scientific computing or hardware test and telemetry • Engineering At SIFT: • You'll have the opportunity to help evolve and scale our platform because we're still in the early stages of building the product. Relevant technologies include: • Web frontend & backend: React, TypeScript, Redux, Tailwind, WebAssembly, D3.js, WebGL, and Go • Web frontend & backend: • Data: Parquet, Flink, Kafka, Redpanda, Beam, DuckDB, Timescale, QuestDB, InfluxDB, and Druid • Infrastructure: GitHub Actions, AWS, Azure, GCP, Docker, Kubernetes, and Terraform • Infrastructure: • Location: • Sift’s headquarters is in Marina Del Rey, CA (Next to LAX). We collaborate in person twice a week—on Mondays and Thursdays—and come together for a full week every two months. We are open to relocating candidates to LA or working from our San Francisco office for the right candidate. • Marina Del Rey, CA • in person • Mondays and Thursdays • relocating candidates to LA • working from our San Francisco • Salary range: $180,000 - $230,000 per year. Plus equity and benefits. • Eligibility: • U.S. Person Required: Must be a U.S. citizen, lawful permanent resident, or protected individual such as an asylee or refugee in compliance with ITAR (International Traffic in Arms Regulations) / EAR (Export Administration Regulations) regulations.

Responsibilities

• Talk directly to customers and partner with product to turn real review workflows into agent capabilities: generating dashboards, writing analysis scripts, and surfacing insights buried in their telemetry • Build the frontend surfaces where Sift Agents live, and make them feel great • Design the interaction patterns of agentic UX: streaming responses, long-running tasks, interruptions, and showing an agent’s work so engineers can trust it • Render an agent’s findings alongside the telemetry that backs them, and keep it fast even when the data is large • Push the browser to its limits when the data demands it: Web Workers, OPFS-backed caching, and stepping outside React when the framework becomes the bottleneck • Contribute to the component library to keep agentic UI patterns consistent across the product • Collaborate with backend and full stack engineers on the API design that powers agent sessions

Benefits

• Estimated Base $180K – $230K • Offers Equity • Offers Benefits • Sift's Guide to Understanding Startup Equity • Sift is the data infrastructure platform for hardware engineering teams. We turn high-frequency telemetry into engineering insights for mission-critical machines: rockets, satellites, autonomous vehicles, energy systems, and defense platforms. Founded by former SpaceX engineers, we are building the review and analysis layer for the AI era of physical systems. • Hardware programs generate far more telemetry than any team can review by hand. Sift Agents is our answer: AI agents that work alongside hardware engineers, investigating anomalies, reviewing test and flight data, and answering in minutes questions that used to take a day of scripting. • This role comes with real product ownership and autonomy. You will talk directly to customers to understand how they review their machines, decide what to build, and own it from first MVP through every iteration after it ships. The surface area is wide: one day you might be polishing the micro-interactions that make the chat experience feel great, the next you might be building a bespoke caching layer for the chat messages off the main JS thread. We’re heavy users of frontier agentic products ourselves and have strong opinions about what makes them great. Sift Agents is where we put those opinions to work. • This is a product engineering role, not a research role. Most of the work is the hard part of making agents feel dependable in the browser: streaming interactions, long-running tasks, rendering agent output over large real-time datasets, and showing engineers exactly what an agent did and why.