Sr. Frontend Engineer

Twenty80 LLC; San Francisco (CA); On-site; USD 180,000 - 230,000; Full time

Job summary

Twenty80 LLC in San Francisco is seeking a Sr. frontend engineer to build and refine our digital platform. You will create interactive interfaces, set engineering standards, and deliver work that users experience directly.

You will lead UI development from concept to production, mentor peers, and collaborate with design and product teams to translate ideas into scalable, accessible applications. This role offers ownership in a fast-growing startup climate with opportunities to influence frontend

Qualifications

• 3–6 years frontend experience in product-focused environments.
• Able to translate designs into accessible, production-ready apps.
• Experience leading substantial frontend projects.
• Mentor team members and contribute to frontend strategy.

Responsibilities

• Own the development of user interfaces from concept to deployment, including maintenance.
• Establish standards for component architecture, coding quality, testing.
• Mentor colleagues and share reusable frontend patterns.
• Collaborate with stakeholders to translate designs into production-ready apps.
• Develop responsive web apps using React, TypeScript, and modern styling.
• Write scalable, well-tested code.
• Decide data flow and component structure.
• Balance speed with quality in a fast-paced environment.

Skills

React

TypeScript

Next.js

CSS frameworks

Component libraries

State management

Testing tools

Accessibility

Job description

San Francisco, CA

About the role

A San Francisco–based startup is looking for a Sr. frontend engineer to build and improve its digital platform. You’ll create interactive user interfaces, set engineering standards, and deliver work that impacts users immediately. This role offers a chance to shape the frontend foundation while contributing to a fast-growing team.

Key Responsibilities

• Own the development of user interfaces from concept to deployment, including ongoing maintenance and monitoring.
• Establish and maintain standards for component architecture, coding quality, and testing practices.
• Mentor colleagues and introduce reusable frontend patterns and best practices.
• Collaborate with stakeholders and end users to clarify requirements and translate designs into production-ready applications.
• Develop responsive web applications using modern frameworks and languages, including React, TypeScript, and contemporary styling systems.
• Write maintainable, well-tested code that scales with the platform.
• Make strategic decisions about data flow, application state, and component structure.
• Work efficiently in a fast-paced environment, balancing speed with quality and user-centered design.

Requirements

• Have 3–6 years of experience delivering frontend systems, particularly in product-focused environments.
• Demonstrate the ability to turn visual designs into accessible, production-ready applications.
• Be deeply interested in user experience, interface design, and product impact—not just code implementation.
• Possess a track record of independently leading substantial projects such as component libraries, feature modules, or performance improvements.
• Serve as a technical reference within the team and contribute to defining frontend strategy.
• Mentor and elevate the skills of other team members.
• Thrive in environments with ambiguous requirements and provide thoughtful, product-minded solutions.

Technical Skills

Core Frontend:

• React, TypeScript, Next.js
• Modern CSS frameworks and component libraries
• Implementation of design workflows from visual tools to code

Data & State Management:

• Application state handling and API integration
• Optimization of rendering and performance

Quality & Reliability:

• Testing frameworks and end-to-end validation tools
• Emphasis on maintainable, scalable code

System & Design Thinking:

• Reusable component strategies and inclusive design principles
• Peer reviews, knowledge sharing, and establishing technical patterns

Preferred Attributes

• Experience as an early engineer or in high-growth startup environments.
• Built shared component ecosystems or internal UI libraries.
• Led frontend technical strategy or guided team practices.
• Worked with analytics or tracking systems to inform product decisions.
• Developed internal tools such as dashboards, admin panels, or operational interfaces.
• Partnered closely with design professionals throughout product development.
• Comfortable with iterative releases and experimental approaches.
• Interest in emerging technologies such as AI, digital commerce, or automation.
• Contributions to personal projects, open source, or community code initiatives.