Senior Frontend Engineer - Performance Optimization

About UsAt thesirius, we're powered by the backing of a16z Speedrun, dedicated to providing innovative solutions that drive growth for top consumer brands. Our advanced technology is relied upon by industry leaders such as Higgsfield and Promova. As we scale our operations, we are on the lookout for talented professionals who are passionate about making impactful contributions to consumer technology advancements. Join our vibrant team where initiative, ambition, and a commitment to excellence in problem-solving are highly valued.Position OverviewIn the role of Senior Frontend Engineer, you will be instrumental in the design, development, and maintenance of the user-facing elements of our core products. Your key responsibilities will include:Crafting and implementing robust, scalable, and user-centric interfaces that accommodate new features and shifting business requirements.Collaborating seamlessly with backend engineers, product managers, and design teams to deliver high-quality, integrated solutions.Providing technical guidance through best practices, mentoring fellow team members, and engaging actively in code reviews.Championing the adoption of contemporary frontend technologies, frameworks, and methodologies to guarantee product quality and maintainability.Identifying and addressing intricate technical challenges pertaining to user experience, performance, and security.Fostering a culture of continuous improvement and operational excellence within the engineering team.QualificationsA minimum of 5 years of professional experience in frontend development for high-traffic applications.Expertise in JavaScript/TypeScript and familiarity with modern frontend frameworks.Proven experience in integrating frontend applications with backend APIs and third-party services.Strong understanding of UI/UX principles, performance optimization, and frontend architecture.Excellent analytical skills with a track record of independently driving projects to successful completion.Full-time availability and a strong passion for contributing to a high-growth, ambitious environment.How to ApplyWe invite you to submit a brief introduction along with your resume for consideration.

About UsAt Finix, we are revolutionizing the way businesses interact with money. As a comprehensive full-stack acquirer processor, we empower organizations of all sizes with innovative and adaptable payment solutions. Annually processing billions in transactions, Finix enables SaaS, marketplace, and e-commerce platforms to effortlessly accept payments, manage payouts, and onboard merchants. Our suite of no-code, low-code, and developer-friendly tools allows businesses to launch in mere hours rather than months.With over $175 million raised, including a significant $75 million Series C round led by Acrew Capital and backed by notable investors such as Lightspeed Venture Partners, American Express Ventures, and Sequoia Capital, we are poised for growth.As a Senior Frontend Engineer on our Frontend Engineering Team, you will play a pivotal role in architecting and constructing the core payment experiences that empower thousands of businesses. You will be responsible for developing our extensive payments management dashboards and embeddable components that merchants integrate into their applications seamlessly.This position allows you to influence the technical vision for customer-facing products from inception through to production. You will lead design and implementation decisions, ensuring our payment interfaces remain high-performing, secure, and user-friendly as we scale. Our engineering team operates with a high degree of autonomy and ownership—each engineer makes impactful contributions that directly enhance customer success in a dynamic fintech landscape.Finix seeks engineers who possess excellent technical skills, a keen eye for detail, a passion for growth, and a dedication to delivering an outstanding customer experience.

About UsAt doss, we are pioneering the future of operational intelligence with our innovative platform—a 'Terraform for operators.' Our AI-generated schema layer powers a customizable data warehouse, enabling companies dealing with physical goods to adapt their record systems in real-time as their business landscape evolves.Imagine leveraging AI foundation models for seamless schema migrations, enjoying real-time observability across operational and financial data, and managing intricate git versioning of schema and data modifications—all while developing workflows akin to infrastructure code.Your RoleDesign and implement the core frontend for our collaborative cloud platform.Take ownership of the technical roadmap for features related to customer-facing experiences.Develop adaptable infrastructure and components that scale in a composable software environment (think tools akin to Retool, Airtable, Zapier, Figma, and Notion).Your ExpertiseAbility to initiate projects from scratch in ambiguous settings.Proficient in Typescript, React, NextJS, and Tailwind CSS.Knowledgeable in GraphQL, Postgres, ORMs, and Node (Express).Competent in utilizing internal APIs to create complex frontend interfaces and components.Skilled in translating intricate Figma UI/UX designs into flawless browser implementations.Your AttributesCollaborative Spirit: You bring enthusiasm, openness, and curiosity to the team every day.Growth-Oriented: You view every experience as an opportunity to learn and uplift the team and company.Dedication to Quality: You take pride in creating high-quality products.Customer-Centric: You are deeply invested in enhancing the customer experience and delivering delightful products.Pragmatic Thinker: You make decisions based on practicality rather than theory.Humble: You thrive in a collaborative atmosphere where everyone contributes to the team’s success.Our BenefitsComprehensive medical, dental, and vision insurance.Unlimited Paid Time Off (PTO) along with mandatory US holidays.401(k) plan with immediate eligibility.Fitness stipends and wellness programs.

About ApiphanyApiphany stands at the forefront of foundational AI technology for physical product development. Our mission is to empower innovators in industries such as automotive, aerospace, medtech, and energy to convert vast amounts of unstructured technical data into real-time, actionable insights. Supported by prominent investors from Markforged, Databricks, GM, and Character, we are dedicated to changing the landscape of engineering decision-making, transforming complexity into clarity for the world's leading manufacturers.Our sophisticated models are tailored to address the intricacies of engineering and manufacturing, comprehending principles of physics, design specifications, and program constraints. We are a tight-knit team of elite builders from top universities including Stanford, Berkeley, MIT, UW, and CMU, alongside industry leaders from GM, Ford, and Genesis Therapeutics. Our passion lies in revolutionizing hard-tech and collaboratively establishing a category-defining enterprise.About the RoleAs a Senior / Staff Frontend Engineer at Apiphany, you will play a crucial role in designing, building, and enhancing our state-of-the-art web application. You will be tasked with implementing high-quality UI components, developing the next generation of data visualization, ensuring optimal performance, and upholding best practices in frontend development.Your contributions will also include shaping the long-term frontend strategy, mentoring team members, and establishing engineering practices that will support the company's growth. You will work closely with design, backend, and machine learning engineers to transform massive data streams into intuitive and actionable insights for users, ensuring a seamless experience.

At Lassie, we are revolutionizing the healthcare industry with our AI-driven solutions designed for medical practices.With over a million health practices spending more than $100 billion annually on administrative staff, the demand for efficient solutions has never been greater. The ongoing effects of COVID-19 have left many offices understaffed, leading to frustrated patients dealing with unanswered calls and confusing bills.We envision a future where AI seamlessly manages the operations of medical offices, handling administrative tasks and serving as the interface for patient interactions.Founded by Steijn Pelle, who propelled Robinhood and Coinbase to substantial revenue milestones, and Frédéric Renken, a former engineer and product pioneer at Superhuman, we are infusing consumer product expertise into healthcare and transforming the way doctors and patients engage.About the RoleWe are seeking a design-oriented Senior Frontend Software Engineer to develop a robust control plane for our powerful AI agents that manage billing and medical records. Your work will impact real patients and practices, as you create interfaces that inspire trust and ease of use.Emphasizing a consumer-friendly approach to healthcare software, we prioritize elegance and meticulous attention to detail. Your contributions will encompass various aspects including onboarding, human-in-the-loop review, and tools that empower practice owners to gain insights into their operations.You Are a Great Fit If You…Pursue excellence and are willing to refine your work until it achieves greatnessTake pride in crafting software that is fast and intuitiveSeek to maximize your impact through automation and effective processesPossess strong foundations in JavaScript and browser APIsShare our belief that healthcare software should be as delightful as consumer applicationsSome of Our Notable AchievementsDeveloped a synchronization engine utilizing encrypted SQLite in the browser, facilitating 100ms response times for healthcare payments and patient ledgersImplemented systems that significantly reduce the paperwork burden by thousands of hours each month

Join Our Innovative Team at AirwallexAt Airwallex, we are revolutionizing the way businesses manage their payments and finances on a global scale. Our unified payments platform leverages cutting-edge technology to empower over 200,000 businesses, including industry leaders like Brex, Rippling, Navan, Qantas, and SHEIN. By joining us, you will be part of a dynamic team that is pushing the boundaries of financial technology.Founded in Melbourne and now boasting over 2,000 talented professionals across 26 offices worldwide, Airwallex is valued at $8 billion and backed by elite investors such as T. Rowe Price, Visa, and Sequoia. If you are eager to make a significant impact in your career, we invite you to be part of our journey.

Important NoticeThis is a full-time, in-person position located in San Francisco (Presidio). We operate from our office five days a week.Candidates must be based in the Bay Area or willing to relocate prior to employment.We require authorization to work in the US, but we are open to O-1 visa sponsorship for outstanding candidates.Your RoleYou will take charge of the frontend aspect of Sauna, delivering interfaces that are seamless, user-friendly, and refined, even when the underlying processes are intricate.You will independently make product and design decisions, rapidly prototype, and implement solutions without being constrained by exhaustive specifications. You may sometimes work from existing designs or create new ones.Technology StackKey technologies include TypeScript, React, Next.js, Y.js, TipTap, and Cloudflare Workers.Who You AreMinimum Qualifications4+ years of experience in frontend engineering with a portfolio that impresses the founders. Show us complex and polished interfaces you've developed.Proficient in TypeScript and React — you are knowledgeable about reconciliation, optimizing renders, and understanding browser behavior.Strong product sense and design intuition — you can interpret a rough product vision, draft user interactions, and create solutions that resonate. You notice when transitions are slightly too slow or when user affordances are ambiguous.Decisive in design — you will need to take ownership of certain UX choices, produce simple designs when necessary, and find paths to overcome obstacles.Autonomous and humble — you do not wait for permission or perfect guidelines. You implement, gather feedback, and improve.Detail-oriented — you care about aspects like loading states, empty states, error messages, and keyboard shortcuts. The myriad small details that enhance software quality matter to you.Preferred Qualifications (not mandatory)Experience with Y.js, Automerge, or CRDTs for real-time collaboration.Familiarity with rich text editors (ProseMirror, TipTap, Slate).Developed interfaces for LLM-based tools (handling streaming responses, uncertainty management, progressive disclosure, etc.).

About WorkWhileAt WorkWhile, we are dedicated to empowering workers to earn a better living and enhance their quality of life. With over 80 million Americans relying on hourly jobs that often come with unpredictable schedules, low wages, and limited benefits, financial stability is often out of reach.We are transforming the landscape of frontline work by fostering a more flexible and efficient labor market. Utilizing advanced AI technology, the WorkWhile platform enables businesses to swiftly access high-quality talent. Our workers enjoy same-day pay, complimentary telehealth services, opportunities for skill enhancement, and the freedom to select shifts that align with their expertise and schedules.With an ambitious goal to align incentives and rectify inefficiencies within the labor market, we are on a mission to disrupt the $650 billion staffing and recruiting industry. Supported by Khosla Ventures and recognized on the Inc. 5000 for 10x growth, WorkWhile is redefining the future of work.

Scribd, Inc. creates products such as Scribd®, Slideshare®, Everand™, and Fable, all with the goal of turning information into insight for users worldwide. The company is dedicated to broadening access to knowledge and expertise on a global level. Culture and Work Style At Scribd, authenticity and bold thinking influence daily decisions and team interactions. Employees are encouraged to share ideas, take initiative, and engage in open dialogue to solve new challenges and meet customer needs. The company’s Scribd Flex policy allows staff to choose their work location and schedule, balanced by planned in-person meetings that help maintain strong team connections. Regardless of where employees live, everyone participates in occasional onsite gatherings to foster collaboration. The company values 'GRIT', a blend of passion and perseverance for long-term goals, which shapes how teams set objectives, innovate, deliver results, and support each other. Quality Engineering Team The Quality Engineering group develops and maintains the testing infrastructure and quality tools that back Scribd’s engineering teams. Their efforts ensure code reliability and support confident releases. Collaboration extends across both the established monolithic codebase and newer microfrontend architectures, with close partnership alongside frontend and platform engineers. Role Overview The Senior Frontend Engineer in Quality Engineering will lead work to expand the quality infrastructure for Scribd’s web engineering teams. As the company moves from a monolithic application toward modular, independently tested components, including microfrontends, this role will help shape the systems that enable that transition. Currently, much of the web platform is still monolithic, with the first microfrontends just entering production. This engineer will design and enhance quality platform capabilities, aiming to increase test ownership, reliability, and developer productivity across all engineering teams.

Join us at datacurve as we revolutionize the developer experience through a gamified platform that inspires tens of thousands of coders to engage in thrilling software engineering challenges – all while advancing the frontiers of large language models (LLMs)!As a Senior Frontend Engineer, you will be a vital member of a dynamic and enthusiastic team committed to tackling complex technical challenges, crafting captivating gamification experiences, and laying the groundwork for a collaborative global developer community.Your ResponsibilitiesCreate and develop user-friendly, visually appealing, and engaging interfaces that attract developers.Work closely with product managers, designers, and backend engineers to create integrated gamified experiences and interactive coding challenges.Design scalable frontend architectures, ensuring maintainability, performance, and reliability as our platform expands.Promote frontend best practices, enhance code quality, and provide mentorship within the engineering team.Engage in continuous experimentation, iteration, and optimization of user experiences driven by analytics and user feedback.Your QualificationsOver 3 years of experience in developing scalable, high-performance frontend applications utilizing React and TypeScript.Expertise in crafting responsive, attractive user interfaces using Tailwind CSS.In-depth knowledge of data fetching, state management, and API integration using GraphQL.Demonstrated ability to design maintainable, modular frontend codebases and implement best practices.Experience in developing and maintaining reusable component libraries and frontend design systems.Familiarity with frontend testing frameworks and best practices (e.g., Vitest, React Testing Library, MSW).A strong passion for creating delightful user experiences and meticulous attention to detail in UI/UX design.A proactive approach to iterating quickly based on user feedback and analytical insights.Preferred QualificationsExperience with Relay for efficient GraphQL data management and client-side caching.Familiarity with frontend code generation tools and workflows (e.g., Plop).Understanding of modern CI/CD practices, including automated testing, linting, and deployment pipelines.

Join Our Mission at 3Y HealthAt 3Y Health, we are revolutionizing the healthcare industry with cutting-edge AI-driven software designed to alleviate the administrative burdens that consume a staggering 40% of healthcare revenue. Our comprehensive platform empowers clinician entrepreneurs, providing them with the tools needed to effectively launch, manage, and grow their private practices. By integrating advanced AI and automation, we enable healthcare providers to reclaim their time, enhance their business operations, and deliver superior outcomes for their communities. We are proud to have secured over $200 million in funding from prestigious investors such as Founders Fund, General Catalyst, Softbank, and 8VC.Your Role as a Frontend EngineerWe are on the lookout for a talented Frontend Engineer who is passionate about crafting intuitive, high-performance user interfaces that resonate with our providers. The ideal candidate will possess extensive knowledge in modern frontend development frameworks, particularly React and TypeScript, coupled with a keen eye for design and user interaction. You will thrive in an environment that values clean, modular code and collaboration with design and product teams to create elegant user experiences. Experience in a startup or as a founding engineer is a plus, showcasing a proactive approach to ownership, speed, and continuous improvement.In this dynamic role, you will influence frontend architecture decisions and work collaboratively across engineering, design, and product teams to enhance our AI-first platform's user experience.

Join Hive as a Senior Frontend Software Engineer!At Hive, we are at the forefront of cloud-based AI solutions, dedicated to revolutionizing the way organizations understand, search, and generate content. Trusted by some of the world's most innovative companies, we empower developers with a suite of top-tier, pre-trained AI models, handling billions of customer API requests each month. Our robust software applications, fueled by proprietary AI models and datasets, are paving the way for groundbreaking use cases in content moderation, brand protection, sponsorship measurement, and context-based advertising.With over $120M raised from esteemed investors such as General Catalyst, 8VC, Glynn Capital, Bain & Company, and Visa Ventures, Hive is proud to employ a diverse team of over 250 talented individuals across our offices in San Francisco, Seattle, and Delhi. If you're ready to shape the future of AI, we want to hear from you!About the RoleAs a Senior Frontend Software Engineer, you will play a pivotal role in developing our Hive Data and Hive Enterprise products. Collaborating closely with designers, product owners, and fellow engineers, you will create innovative user interfaces that define our platforms. Utilizing the latest web technologies, including React, Redux, Webpack, and ES6, you will deliver exceptional user experiences. Given our small, agile team, you will have the opportunity to iterate rapidly and make impactful software design decisions regarding product features. We seek candidates with a strong technical foundation who are passionate about frontend technologies and thrive in a dynamic, fast-paced environment.

About the Role HeartFlow, Inc. is looking for a Senior Frontend Software Engineer in San Francisco, California. This role focuses on designing and building user interfaces for advanced cardiovascular imaging products. The work centers on creating intuitive, reliable experiences for clinicians and patients. What You Will Do Design and implement frontend features for cardiovascular imaging solutions Collaborate with product, design, and backend teams to deliver high-quality user interfaces Contribute expertise to improve usability and performance Collaboration This position works closely with cross-functional teams to ensure that user needs and technical requirements align throughout the development process.

About GigaGiga has successfully secured $61 million in Series A funding and boasts a diverse client portfolio that includes industry leaders like DoorDash. We are on a mission to revolutionize customer experiences by developing real-time AI agents capable of understanding emotions, resolving issues instantly, and scaling to meet the demands of the world's largest enterprises.This is a pivotal moment in our journey. While we have achieved significant milestones, our ambitions extend further. Our vision is to establish ourselves as the premier AI platform for enterprise automation, driven by our voice superintelligence. To bring this vision to life, we are on the lookout for exceptional engineers.The work we do impacts millions of users daily, and our engineers enjoy a high degree of autonomy, making a tangible impact. This is a unique opportunity to join a company with visionary founders, a proven track record of commercial success, and a clear trajectory towards becoming a generational powerhouse. Here are some highlights about us:Voice AI startup Giga raises $61M Series ADoorDash and Giga PartnershipIf this mission resonates with you, we invite you to apply!Why Join Us in this Role?Momentum: Become part of a team recognized by both customers and investors.Ownership: Play a vital role in innovative projects that transform industries and shape the company's technical and product direction.Growth: Advance your skills alongside top-tier engineers and visionary founders.More About the RoleWe are searching for an experienced Senior Frontend Engineer with a strong background in creating functional and visually engaging user experiences. You will spearhead the design and development of our frontend applications that users interact with daily, collaborating closely with product managers, designers, and backend engineers.What You’ll DoOwn the Frontend: Quickly contribute to our products and lead the development of design systems.Craft Seamless UX: Develop responsive, accessible, and high-performance interfaces for enterprise users.

Compensation: Competitive base salary with significant equity options.Benefits: Comprehensive health and dental insurance, gym reimbursement, and daily team lunches.At Julius, we are pioneering an applied AI lab focused on developing coding agents. Our mission is to empower one billion individuals to become software creators, starting with innovative data science and analysis applications.Currently, our team has successfully executed 1 million lines of code every 36 hours, catering to over 1 million users while generating more than 3 million data visualizations.Our compact technical team comprises professionals with backgrounds from top companies such as Uber, Microsoft, and Facebook. We are generating revenue and are proudly supported by prominent investors, including AI Grant and founders from Vercel, Notion, Perplexity, Palantir, Replit, Zapier, Intercom, Dropbox, as well as researchers from OpenAI and Google DeepMind.Creating intuitive and high-performance user interfaces is essential for ensuring that Julius remains user-friendly for our vast audience. Our interface encompasses various components such as tool utilization, multi-step reasoning, code generation, execution, file management, and more. In this role, you will have the opportunity to define and build experiences across these elements as we expand toward our future objectives.

Join our dynamic team at SoFi Technologies as a Senior Frontend Engineer specializing in cryptocurrency solutions. We're at the forefront of financial technology, transforming the way people manage their finances. You will play a crucial role in developing user-centric applications that empower our customers to navigate the world of digital currencies seamlessly.

Join Filevine, a pioneering Legal AI firm revolutionizing legal work with our cutting-edge Legal Operating Intelligence platform. We unite data, documents, workflows, and teams into a cohesive system that enhances clarity and consistency in modern legal practice.With our innovative Legal Operating Intelligence System (LOIS), we empower legal professionals to shift from reactive to proactive operations. LOIS comprehensively analyzes your data to uncover insights, automate complex processes, and provide the clarity needed to excel. Recognized by Deloitte and Inc. as a leader in technological innovation, Filevine is experiencing rapid growth and is proud to be a top player in the industry.Position Overview:We are seeking a talented Senior or Staff Frontend Engineer to take ownership of essential product features across our Word and web applications. In this role, you will establish high standards for user interface quality, influence architectural choices, and collaborate closely with design, backend, and AI engineering teams. Your contributions will directly impact the workflows of thousands of legal teams daily.This is an opportunity for individuals looking for significant ownership, rapid iteration cycles, and substantial influence within one of Filevine’s most technical and user-oriented product areas.

About the Role Hinge Health is hiring a Senior Frontend Software Engineer in San Francisco (HQ). This role focuses on developing user interfaces that help patients engage with digital health tools. The work directly supports the company’s goal of making healthcare more accessible and effective.

At Sift, we're revolutionizing the way modern machines are constructed, tested, and managed. Our innovative platform provides engineers with real-time insights into high-frequency telemetry, effectively removing bottlenecks and facilitating quicker, more reliable development processes.Sift originated from our work at SpaceX, where we tackled projects like Dragon, Falcon, Starlink, and Starship. The need for scalable telemetry, efficient debugging of flight systems, and guaranteed mission reliability pushed us to create new infrastructure. Founded by a team of experts from SpaceX, Google, and Palantir, Sift is designed for mission-critical applications where accuracy and scalability are paramount.As an early engineer at Sift, your role extends beyond merely coding; you will define the architecture, shape the product, and influence the company's culture focused on addressing significant engineering challenges. If you seek complex technical problems and the chance to build foundational systems for sophisticated machinery from the ground up, we want to connect with you.