Principal Engineer (frontend)

About the Role

As a Principal Front-end Engineer at Sage, you will provide technical leadership in designing, developing, and delivering a high-quality SaaS solution that exceeds customer and business partner expectations. We are looking for someone with 10+ years of professional experience in frontend engineering, who can bring technical depth, architectural vision, and leadership maturity to the team. Proficiency in English, written and verbal, is required.

We value humility and collaboration. We are looking for people who can work as part of a team, not in silos. We expect engineers to take ownership beyond just writing code, including tests, documentation, and long-term code quality.

Location: Bangalore, India. This is a hybrid role, three days per week in the office.

Required Skills Core languages & frameworks

• Strong TypeScript (strict) and modern JavaScript (ES Modules, async).
• Deep React experience (hooks, composition, performance); React 19 / React Compiler a plus.
• Solid HTML5, CSS3, and responsive/accessible UI fundamentals.

Build & tooling

• Modern build tooling Vite (or Webpack/Rollup); code splitting and bundle optimization.
• Git and pull-request workflows; monorepo experience (Nx) a plus.
• Linters/formatters (Biome, ESLint/Prettier) and CI discipline.

State & data

• State management with Redux Toolkit, XState (state machines), and/or TanStack Query.
• RxJS / reactive streams.
• Consuming REST APIs; JWT/OAuth2 bearer auth on the client; robust error handling.

Styling & design systems

• Tailwind CSS, MUI (Material UI), styled-components/Emotion.
• Working with a design-token system for brand consistency.

Data grids & performance

• Complex data grids (ag-Grid Enterprise preferred, or TanStack Table/Handsontable): virtualization, server-side row model, custom renderers/editors.
• Frontend performance profiling and optimization (rendering, memoization, main-thread work).
• Web Workers for off-main-thread compute.

Accessibility & i18n

• WCAG 2.1/2.2 AA accessibility practices; ARIA, keyboard, focus management.
• Internationalization (i18next or similar), including locale-aware date/number formatting.

Testing & quality

• Unit/component testing (Vitest/Jest + Testing Library), API mocking (MSW), and Playwright E2E.
• Secure client-side coding against the OWASP Top 10 (XSS, token handling, safe storage).

AI Tooling

• Productive use of AI-assisted developer tooling (e.g. GitHub Copilot, Claude Code, Cursor) to accelerate day-to-day frontend development.
• Building AI-assisted / generative-AI UX: in-app copilots, natural-language querying, or smart suggestions surfaced to the user.
• Integrating LLM APIs on the client (e.g. OpenAI, Anthropic, AWS Bedrock) with streaming/token-by-token rendering, cancellation, and graceful error/loading states.

Nice to Have

• Web Crypto / AES-GCM application-level encryption and client-side key management.
• Lexical (or ProseMirror/Slate) rich-text/formula editors; grammar parsing (ohm-js).
• Dependency-graph / DAG modeling (graphlib/graphology).
• CRDT / operational-transform real-time collaboration.
• Storybook and visual regression testing.
• New Relic browser RUM, Pendo, and web-vitals (INP/FPS) instrumentation.
• Experience meeting enforced performance budgets and SLOs in CI.
• Domain knowledge in finance, ERP, FP&A, budgeting, or spreadsheet-like applications.
• Designing accessible, trustworthy AI interaction patterns, such as citations, confidence indicators, and human-in-the-loop review for sensitive outputs.

Responsibilities Key Responsibilities

• Define and enforce frontend best practices, coding standards, and design systems.
• Act as a final reviewer for critical frontend design and implementation decisions.
• Mentor engineers, provide constructive feedback, and build a strong culture of technical excellence.
• Break down complex initiatives into milestones, estimate effectively, and deliver high-quality features with minimal oversight.
• Collaborate across Product, Backend, and Support teams to ensure smooth delivery and long-term maintainability.
• Growth mindset: you are curious, always learning, and open to feedback.
• Strong collaboration skills: you work well with peers and cross-functional partners, and you know great ideas can come from anywhere.