Senior Frontend Engineer

About the Company

HumanSignal is a human data partner for companies building AI models and products. We design and create datasets from scratch, recruit and manage domain experts, and run everything through our own platform, Label Studio, the open-source standard for data labeling and evaluation.

Responsibilities

• Build and maintain frontend components and views for labeling, review, and evaluation workflows
• Own outcomes by refining scope, suggesting trade-offs, and proposing simpler approaches
• Partner with Product & Design from discovery to delivery to shape scope and milestones
• Prototype to de-risk UX and use feature flags for gradual rollouts
• Raise the bar on FE standards including state management, testing, accessibility, and i18n
• Partner with Support to investigate production issues and reduce UX papercuts
• Engage with the open-source community to understand real-world needs
• Participate in architecture discussions, code reviews, and mentor teammates

Requirements

• Senior-level experience shipping production React/TypeScript apps
• Mastery of HTML/CSS, ES6+, and accessibility (a11y)
• Strong product sense with experience making scope and trade-off decisions
• Fluency with modern FE tooling such as Vite, Webpack, Jest, or Cypress
• Experience with state-management patterns
• Comfort collaborating with APIs and familiarity with Django/REST is a plus
• Excellent communication skills for writing RFCs/PRDs and providing actionable reviews

Preferred Qualifications

• Experience with data/ML tools or open-source software
• Experience with design systems or performance profiling
• Familiarity with feature flags and qualitative feedback loops
• Prior work on complex, data-heavy UIs like review tools or multi-step workflows