Frontend Engineer (Mid)

Konnco Studio; Daerah Istimewa Yogyakarta; On-site; IDR 89,280,000 - 156,240,000; Full time

Job summary

Konnco Studio in Indonesia is seeking a frontend engineer with 1-2 years of experience to build and maintain client web apps primarily in React. You will contribute to internal libraries, integrate REST APIs with token-based auth, and adapt to Vue/Svelte/Solid when needed.

You will ensure security, performance, and code quality with Vitest/Jest, Git workflows, and close collaboration with design, QA, and clients. Familiarity with fintech is a plus; strong communication is essential.

Qualifications

• 1-2 years of frontend engineering experience, preferably in fintech.
• Strong React skills with hooks, composition, state management and performance.
• Able to reason about component-based frameworks and adapt quickly to Vue/Svelte/Solid.
• REST API integration with token-based auth (JWT/OAuth).
• Frontend security awareness (XSS/CSRF, safe token handling, no PII in logs).
• Git usage including branches, PRs, and code review.
• Figma proficiency for reading specs and assets.
• Testing experience with Vitest or Jest, including mocks and coverage.
• Precise handling of monetary values (formatting, rounding, currency).
• Clear communication, able to explain decisions and flag blockers early.

Responsibilities

• Build and maintain client web applications, primarily in React.
• Contribute to internal shared libraries — API design, versioning, docs, and release.
• Pick up alternative frameworks (Vue, Svelte, Solid) as projects require.
• Integrate REST APIs, including auth flows and error handling.
• Optimize rendering performance and bundle size.
• Write and maintain unit/component tests with Vitest to ensure code reliability.
• Collaborate with backend, design, QA, and client stakeholders.

Skills

React

Vue familiarity

Svelte familiarity

Solid familiarity

REST API

JWT/OAuth

Security awareness

Code reviews

Communication

Monetary formatting

Tools

Git

Figma

Vitest/Jest

Job description

• Build and maintain client web applications, primarily in React
• Contribute to internal shared libraries — API design, versioning, docs, and release
• Pick up alternative frameworks (Vue, Svelte, Solid) as projects require
• Integrate REST APIs, including auth flows and error handling
• Optimize rendering performance and bundle size
• Write and maintain unit/component tests with Vitest to ensure code reliability and prevent regressions
• Collaborate with backend, design, QA, and client stakeholders

Qualifications & Tech Skills

• 1-2 years of frontend engineering experience, preferably in fintech
• Strong React skills, including hooks, composition, state management, and performance optimization
• Able to reason about component-based frameworks from first principles and adapt quickly to new ones like Vue, Svelte, or Solid
• REST API integration, including token-based auth with JWT or OAuth
• Frontend security awareness, covering XSS/CSRF, safe token handling, and avoiding PII in client logs
• Git proficiency (mandatory), including branching, pull requests, and code review
• Figma proficiency (mandatory), including reading specs and extracting assets, components, and variants
• Testing experience with Vitest or similar frameworks like Jest, including mocking and coverage
• Precision working with monetary values, such as formatting, rounding, and currency handling
• Clear team communication, able to explain decisions, handle code review, and flag blockers early

Nice to Have

React Native or interest in mobile development, native Android/iOS modules, experience with Vue, Svelte, or Solid, shared library or design system maintenance (semver, npm publishing, monorepo tooling), TypeScript, fintech or payments background, CI/CD, Next.js or React Router, and agency or client-project experience.